FUSION PROTEINS AND PHARMACEUTICALS CONTAINING THESE FUSION PROTEINS

Abstract

The invention relates to an antigen-binding molecule against CD8 and a fusion polypeptide containing an antigen-binding molecule for the selective modulation of CD8+ T cell function over other immune cells. In addition, the invention relates to the polynucleotide encoding the antigen-binding molecule and the fusion polypeptide that has been expressed, and the vector and host cell containing this polynucleotide. Furthermore, the invention relates to a method for producing the antigen-binding molecule and the fusion polypeptide, pharmaceuticals containing them, and their applications.

Description

FUSIONS WITH CD8 ANTIGEN BINDING MOLECULES FOR MODULATING IMMUNE CELL FUNCTION CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of U.S. Provisional Application Nos. 63 / 105,162, filed October 23, 2020; 63 / 121,663, filed December 4, 2020; and 63 / 190,669, filed May 19, 2021; each of which is hereby incorporated by reference in its entirety. SUBMISSION OF SEQUENCE LISTING ON ASCII TEXT FILE

[0002] The content of the following submission on ASCII text file is incorporated herein by reference in its entirety: a computer readable form (CRF) of the Sequence Listing (file name: 182842000440SEQLIST.TXT, date recorded: October 21, 2021, size: 557,283 bytes). FIELD

[0003] The present disclosure discloses CD8 antigen binding molecules and fusion polypeptides comprising the CD8 antigen binding molecules for selectively modulating the function of CD8+ T cells over other immune cells. In addition, the present disclosure also provides polynucleotides encoding the disclosed antigen binding molecules and fusion polypeptides, and vectors and host cells comprising such polynucleotides. The present disclosure further provides methods for producing the antigen binding molecules and fusion polypeptides, pharmaceutical compositions comprising the same, and uses thereof. BACKGROUND

[0004] CD8+ T cells expressing alpha beta T cell receptors are a large subset of major histocompatibility (MHC) class I-restricted T cells that mediate adaptive immunity to various pathogens and cancers. In addition, they can also be pathogenic and cause disease in certain autoimmune and inflammatory conditions. Modulating the function of CD8+ T cells, either by activating their function in the context of infection and cancer, or by inhibiting their function in the context of certain autoimmune diseases, can have therapeutic benefits.

[0005] CD8+ T cell activation and differentiation is in large part controlled by soluble immunomodulatory proteins such as cytokines. Biological activity of cytokines is mediated by binding to their respective cytokine receptors on the cell surface, typically with very high affinity, resulting in their ability to potently stimulate signal transduction downstream of theirreceptors triggering various cellular processes that regulate immune cell phenotype and function. Cytokines typically have pleiotropic effects, causing multiple downstream cellular events such as activation, proliferation, survival, apoptosis, and secretion of other immunomodulatory proteins. In addition, because their receptors are expressed on multiple immune cell subsets, cytokines act not only on CD8+ T cells but also on other immune and non-immune cells that express their receptors.

[0006] For example, interleukin-2 (IL-2) is a cytokine that regulates many lymphocyte subsets, including alpha beta CD4+ and CD8 T+ cells, and various innate and innate-like lymphocytes such as NK cells, NK T cells, gamma delta T cells (TȖį) cells, and innate lymphoid cells (ILC1, ILC2, and ILC3 cells).

[0007] IL-2 can signal by binding with an intermediate affinity to a receptor complex consisting of IL-2Rȕ and IL-2RȖ subunits (IL-2RȕȖ, intermediate affinity receptor), both of which are required and sufficient to trigger downstream signaling in immune cells. In addition, IL-2 binds with high affinity to a receptor complex consisting of IL-2RĮ, IL-2Rȕ, and IL-2RȖ subunits (IL-2RĮȕȖ, high affinity receptor) (Stauber et al, Proc Natl Acad Sci U S A. 2006 Feb 21;103(8):2788-93). IL-2RĮ expression is restricted to CD4+ Treg cells, activated T lymphocytes, and ILC2 and ILC3 cells, making these subsets the most sensitive to IL-2 signaling. IL-2Rȕ and IL-2RȖ subunits are shared with another related cytokine, IL-15, and IL- 2RȖ subunit is shared among other common gamma chain cytokines (IL-4, IL-7, IL-9, and IL- 21). Most innate and innate-like lymphocytes including NK cells, NK T cells, TȖį cells, and ILC1, ILC2, and ILC3 cells express high levels of IL-2Rȕ (ImmGen consortium; Heng TS et al, Immunological Genome Project Consortium. Nat Immunol.2008 Oct;9(10):1091-4), which also makes them sensitive to both IL-2 and IL-15 cytokines.

[0008] Binding of IL-2 to its receptor induces the phosphorylation of receptor-associated Janus kinases, JAK3 and JAK1, which promote the phosphorylation of STAT5 transcription factor (pSTAT5) that regulates transcription of many genes in lymphocytes. IL-2 signaling in lymphocytes promotes cell survival, proliferation, and increased effector function, including pro- inflammatory cytokine secretion and cytotoxic function, and in some cases, activation-induced cell death (reviewed in Ross & Cantrell, Annu Rev Immunol. 2018 Apr 26;36:411-433).

[0009] CD8+ T cells express CD8, which is a type I transmembrane glycoprotein found on the cell surface as a CD8 alpha (CD8Į, CD8a) homodimer and CD8 alpha-CD8 beta (CD8ȕ, CD8b) heterodimer. CD8 dimers interact with the MHC class I molecules on target cells and this interaction keeps the TCR closely engaged with MHC during CD8+ T cell activation. The cytoplasmic tail of CD8Į contains binding sites for a T cell kinase (Lck) that initiates signal transduction downstream of the TCR during T cell activation, while the role of CD8ȕ is thought to be in increasing the avidity of CD8 binding to MHC class I and influencing specificity of the CD8 / MHC / TCR interaction (Bosselut et al, Immunity.2000 Apr;12(4):409-18). TCR alpha beta- expressing CD8+ T cells typically express both CD8ab and CD8aa dimers, however high levels of CD8aa but not CD8ab dimers can be found on some innate lymphocytes such as NK cells, mucosal-associated invariant T (MAIT) cells, and gamma delta T cells.

[0010] Accordingly, there is a need for antibodies that selectively bind to CD8ab heterodimers over CD8aa homodimers. These antibodies can be used, e.g., for targeting certain immunomodulatory polypeptides, such as IL-2, to CD8ab+ T cells, and limiting their activity on CD8- immune cells and CD8aa+ immune cells such as NK cells.

[0011] All references cited herein, including patent applications, patent publications, and UniProtKB / Swiss-Prot Accession numbers are herein incorporated by reference in their entirety, as if each individual reference were specifically and individually indicated to be incorporated by reference. BRIEF SUMMARY

[0012] The present disclosure describes, inter alia, human or humanized antibodies, antigen binding fragments, and fusion proteins that bind human CD8b. In some embodiments, the human or humanized antibodies, antigen binding fragments, and fusion proteins bind human CD8b or a human CD8ab heterodimer preferentially over binding to a human CD8aa homodimer In some embodiments, the human or humanized antibodies, antigen binding fragments, and fusion proteins bind CD8b, CD8ab, or both.

[0013] Certain aspects of the present disclosure relate to human or humanized antibodies or antigen binding fragments thereof. In some embodiments, the antibody or fragment specifically binds human CD8b and / or human CD8ab with at least 10-fold higher affinity than its binding to human CD8a and / or human CD8aa In some embodiments the antibody or fragment specificallybinds the extracellular domain(s) of human CD8b and / or human CD8ab with at least 10-fold higher affinity than its binding to the extracellular domain(s) of human CD8a and / or human CD8aa. In some embodiments, the antibody or fragment binds to a cell expressing a human CD8ab heterodimer on its surface with an EC50 that is less than 1000nM. In some embodiments, the antibody or fragment binds human CD8+ T cells. In some embodiments, the antibody or fragment specifically binds human CD8b and / or human CD8ab with at least 10-fold higher affinity than its binding to human CD8a and / or human CD8aa expressed on the surface of an natural killer (NK) cell. In some embodiments, the antibody or fragment specifically binds a cell expressing human CD8b and / or human CD8ab on its surface (e.g., a T cell) with at least 10- fold higher affinity than its binding to a cell expressing human CD8a and / or human CD8aa on its surface (e.g., an NK cell).

[0014] In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:63. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67. In some embodiments, the antibody orfragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:71. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence ofSEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:186.

[0015] In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of X1X2AIS, wherein X1 is S, K, G, N, R, D, T, or G, and wherein X2 is Y, L, H, or F (SEQ ID NO:259), a CDR-H2 comprising the amino acid sequence of X1X2X3PX4X5X6X7X8X9YX10QKFX11G, wherein X1 is G or H, X2 is I or F, X3 is I, N, or M, X4is G, N, H, S, R, I, or A, X5is A, N, H, S, T, F, or Y, X6is A, D, or G, X7is T, E, K, V, Q, or A, X8is A or T, X9is N or K, X10is A or N, and X11is Q or T (SEQ ID NO:260), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3 is A, L, P, or Y, X4 is I or L, X5 is R, A, Q, or S, X6 is A or D, and X7 is D, E, A, or S (SEQ ID NO:261); and wherein the VL domain comprises a CDR- L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1 is R or G, X2 is A or T, X3 is Q or E, X4 is E, N, T, S, A, K, D, G, R, or Q, X5 is Y or S, and X6 is A or V (SEQ IDNO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1is A or S, X2is T, S, E, Q, or D, X3is N, R, A, E, or H, X4is Q or A, and X5is S or D (SEQ ID NO:263), and a CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1 is S, N, D, Q, A, or E, X2 is T, I, or S, X3 is Y, L, or F, X4 is D, G, T, E, Q, A, or Y, and X5 is A, T, R, S, K, or Y (SEQ ID NO:264). In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:251; and the VL domain comprises the amino acid sequence of SEQ ID NO:252. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; andwherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequence RVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0016] In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of GX1X2FX3X4X5, wherein X1is G, Y, S, or A,X2is T, S, G, R, N, or H, X3is S, T, R, H, Y, G, or P, X4is S, K, G, N, R, D, T, or G, and X5isY, L, H, or F (SEQ ID NO:265), a CDR-H2 comprising the amino acid sequence of X1PX2X3X4X5, wherein X1 is I, N, or M, X2 is G, N, H, S, R, I, or A, X3 is A, N, H, S, T, F, or Y, X4 is A, D, or G, and X5 is T, E, K, V, Q, or A (SEQ ID NO:266), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1 is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3is A, L, P, or Y, X4is I or L, X5is R, A, Q, or S, X6is A or D, and X7is D, E, A, or S (SEQ ID NO:267); and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1is R or G, X2is A or T, X3is Q or E, X4is E, N, T, S, A, K, D, G, R, or Q, X5 is Y or S, and X6 is A or V (SEQ ID NO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1 is A or S, X2 is T, S, E, Q, or D, X3 is N, R, A, E, or H, X4 is Q or A, and X5 is S or D (SEQ ID NO:263), and a CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1 is S, N, D, Q, A, or E,X2is T, I, or S, X3is Y, L, or F, X4is D, G, T, E, Q, A, or Y, and X5is A, T, R, S, K, or Y (SEQ ID NO:264). In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246. In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:251; and the VL domain comprises the amino acid sequence of SEQ ID NO:252. In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS(SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0017] In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of X1YX2MS, wherein X1 is S, D, E, A, or Q and X2 is A, G, or T (SEQ ID NO:268), a CDR-H2 comprising the amino acid sequence of DIX1X2X3GX4X5TX6YADSVKG, wherein X1 is T, N, S, Q, E, H, R, or A, X2 is Y, W, F, or H, X3 is A, S, Q, E, or T, X4 is G or E, X5 is S or I, and X6 is A or G (SEQ ID NO:269), and a CDR- H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1is S or A, X2is N, H, A, D, L, Q, Y, or R, X3is A, N, S, or G, X4is A, V, R, E, or S, X5is D or S, X6is D, N, Q, E, S, T, or L, X7is L, F, or M, and X8is I, Y, or V (SEQ ID NO:270) and a VL domain comprising a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42). In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequenceof SEQ ID NO:248. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:249, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:250. In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0018] In some embodiments, the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of GFTFX1X2Y, wherein X1 is S, D, E, Q, S, or A and X2 is S, D, E, A, or Q (SEQ ID NO:271), a CDR-H2 comprising the amino acid sequence of X1X2X3GX4X5, wherein X1 is T, N, S, Q, E, H, R or A, X2 is Y, W, F, or H, X3 is A, S, Q, E, or T, X4 is G or E, and X5 is S or I (SEQ ID NO:272), and a CDR-H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1is S or A, X2is N, H, A, D, L, Q, Y, or R, X3is A, N, S, or G, X4is A, V, R, E, or S, X5is D or S, X6is D, N, Q, E, S, T, or L, X7is L, F, or M, and X8is I, Y, or V (SEQ ID NO:273); and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42). In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:249, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:250. In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAAS (SEQ ID NO:286), a FW-2 comprising the sequence AMSWVRQAPGKGLEWVSDI (SEQ ID NO:287), a FW-3 comprising the sequence TAYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:288), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0019] In some embodiments according to any of the embodiments described herein, the antibody is a multispecific antibody (e.g., a bispecific antibody).

[0020] Further provided herein are fusion proteins comprising a first moiety comprising the antibody or fragment of any one of the above embodiments and a second moiety comprising a cytokine, chemokine, or growth factor. In some embodiments, the first moiety is fused to the second moiety directly or via a linker. In some embodiments, the first moiety comprises a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16 a CDR L2 comprising the amino acid sequence of SEQ ID NO:17 and aCDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domaincomprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR- L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42); the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR- L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42). In some embodiments, the first moiety comprises a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR- H3 comprising the amino acid sequence of SEQ ID NO:27, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprisingthe amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42.

[0021] In some embodiments according to any of the embodiments described herein (e.g., a fusion protein of the present disclosure), the second moiety induces activation of CD8+ T cells. In some embodiments, the fusion protein induces activation of cells expressing a human CD8ab heterodimer with at least 10-fold higher potency than activation of cells expressing a human CD8aa homodimer. In some embodiments, the fusion protein induces activation of CD8+ T cells with at least 10-fold higher potency than activation of NK cells. In some embodiments, potency of activation is measured by EC50, as assessed by cell proliferation. In some embodiments, the first moiety comprises two antibody heavy chain polypeptides comprising a structure according to formula [I], from N-terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I] and two antibody light chain polypeptides comprising a structure according to formula [II], from N-terminus to C-terminus: VL-CL [II] wherein VH is an antibody heavy chain variable (VH) domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is an antibody light chain variable (VL) domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of one of the two CH3 domains (e.g., via a linker of the present disclosure). In some embodiments, the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N-terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I],an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is an antibody heavy chain variable (VH) domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is an antibody light chain variable (VL) domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the second antibody heavy chain polypeptide (e.g., via a linker of the present disclosure). In some embodiments, the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the first antibody heavy chain polypeptide (e.g., via a linker of the present disclosure).In some embodiments, the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N- terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is an antibody heavy chain variable (VH) domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is an antibody light chain variable (VL) domain, and wherein CL is an antibody constant light chain domain; and wherein the C-terminus of the second moiety is fused to the N-terminus of the hinge domain of the second antibody heavy chain polypeptide (e.g., via a linker of the present disclosure). In some embodiments, the first moiety comprises one or two antibody heavy chain polypeptides and one or two antibody light chain polypeptides. In some embodiments, the first moiety comprises a single chain antibody or single chain variablefragment (scFv). In some embodiments, the first moiety comprises a VHH antibody. In some embodiments according to any of the embodiments described herein (e.g., the fusion proteins described above), VH and VL form an antigen binding site (e.g., that specifically binds CD8b and / or CD8ab). In some embodiments, the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N-terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the first antibody heavy chain polypeptide. In some embodiments, the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising theamino acid sequence of SEQ ID NO:27, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179, and wherein the VL domain of both antibody lightchain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising theamino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acidsequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR- L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain of both antibody heavy chain polypeptides comprises a CDR- H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain of both antibody heavy chain polypeptides comprises a CDR- H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence ofSEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain of both antibody heavy chain polypeptides comprises a CDR- H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the aminoacid sequence of SEQ ID NO:27, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227, and wherein the VL domain comprises a CDR-L1comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21, and wherein the VL domain comprises a CDR-L1 comprisingthe amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR- H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acidsequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR- H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242, and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to thesequence of SEQ ID NO:63; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:71; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:186; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequencethat is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252; the VH domain comprises the amino acid sequence of SEQ ID NO:251, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:252; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250; the VH domain comprises the amino acid sequence of SEQ ID NO:249, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:250; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256; or the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or100% identical to the sequence of SEQ ID NO:63; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:71; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:186; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252; the VH domain comprises the amino acid sequence of SEQ ID NO:251, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:252; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253, and wherein the VLdomain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250; the VH domain comprises the amino acid sequence of SEQ ID NO:249, and wherein the VL domain comprises the amino acid sequence of SEQ ID NO:250; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256; or the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258. In some embodiments, one or both of the antibody heavy chain polypeptides comprise(s) the following amino acid substitutions: L234A, L235A, and G237A, numbering according to EU index. In some embodiments, a first of the antibody heavy chain polypeptides comprises amino acid substitutions Y349C and T366W, and a second of the antibody heavy chain polypeptides comprises amino acid substitutions S354C, T366S, L368A and Y407V, numbering according to EU index.

[0022] In some embodiments according to any of the embodiments described herein, the second moiety comprises an IL-2 polypeptide. In some embodiments, the IL-2 polypeptide is a mutant IL-2 polypeptide comprising one or more mutations relative to a human IL-2 polypeptide comprising the sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTFKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:81). In some embodiments, the mutant IL-2 polypeptide has a bi di ffi it t IL 2RD th t i d d b 50% d t bi di ffi it fwild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2Rɲ^^ In some embodiments, the mutant IL-2 polypeptide has a binding affinity to IL-2Rɴ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2Rɴ; and / or the mutant IL-2 polypeptide has a binding affinity to IL-2RȖ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2RȖ. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one, two, three, four, or five amino acid substitutions relative to SEQ ID NO:81, and wherein the one, two, three, four, or five substitution(s) comprise substitution(s) at positions of SEQ ID NO:81 selected from the group consisting of: Q11, H16, L18, L19, D20, Q22, R38, F42, K43, Y45, E62, P65, E68, V69, L72, D84, S87, N88, V91, I92, T123, Q126, S127, I129, and S130. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E and F42A; R38D and F42A; F42A and E62Q; R38A and F42K; R38E, F42A, and N88S; R38E, F42A, and N88A; R38E, F42A, and N88G; R38E, F42A, and N88R; R38E, F42A, and N88T; R38E, F42A, and N88D; R38E, F42A, and V91E; R38E, F42A, and D84H; R38E, F42A, and D84K; R38E, F42A, and D84R; H16D, R38E and F42A; H16E, R38E and F42A; R38E, F42A and Q126S; R38D, F42A and N88S; R38D, F42A and N88A; R38D, F42A and N88G; R38D, F42A and N88R; R38D, F42A and N88T; R38D, F42A and N88D; R38D, F42A and V91E; R38D, F42A, and D84H; R38D, F42A, and D84K; R38D, F42A, and D84R; H16D, R38D and F42A; H16E, R38D and F42A; R38D, F42A and Q126S; R38A, F42K, and N88S; R38A, F42K, and N88A; R38A, F42K, and N88G; R38A, F42K, and N88R; R38A, F42K, and N88T; R38A, F42K, and N88D; R38A, F42K, and V91E; R38A, F42K, and D84H; R38A, F42K, and D84K; R38A, F42K, and D84R; H16D, R38A, and F42K; H16E, R38A, and F42K; R38A, F42K, and Q126S; F42A, E62Q, and N88S; F42A, E62Q, and N88A; F42A, E62Q, and N88G; F42A, E62Q, and N88R; F42A, E62Q, and N88T; F42A, E62Q, and N88D; F42A, E62Q, and V91E; F42A, E62Q, and D84H; F42A, E62Q, and D84K; F42A, E62Q, and D84R; H16D, F42A, and E62Q; H16E, F42A, and E62Q; F42A, E62Q, and Q126S. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with a further amino acid substitution relative to SEQ ID NO:81 at position C125. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to thesequence of SEQ ID NO:81): R38E, F42A, and C125A; R38D, F42A , and C125A; F42A, E62Q, and C125A; R38A, F42K, and C125A; R38E, F42A, N88S, and C125A; R38E, F42A, N88A, and C125A; R38E, F42A, N88G, and C125A; R38E, F42A, N88R, and C125A; R38E, F42A, N88T, and C125A; R38E, F42A, N88D, and C125A; R38E, F42A, V91E, and C125A; R38E, F42A, D84H, and C125A; R38E, F42A, D84K, and C125A; R38E, F42A, D84R, and C125A; H16D, R38E, F42A, and C125A; H16E, R38E, F42A, and C125A; R38E, F42A, C125A and Q126S; R38D, F42A, N88S, and C125A; R38D, F42A, N88A, and C125A; R38D, F42A, N88G, and C125A; R38D, F42A, N88R, and C125A; R38D, F42A, N88T, and C125A; R38D, F42A, N88D, and C125A;R38D, F42A, V91E, and C125A; R38D, F42A, D84H, and C125A; R38D, F42A, D84K, and C125A; R38D, F42A, D84R, and C125A; H16D, R38D, F42A, and C125A; H16E, R38D, F42A, and C125A; R38D, F42A , C125A, and Q126S; R38A, F42K, N88S, and C125A; R38A, F42K, N88G, and C125A; R38A, F42K, N88R, and C125A; R38A, F42K, N88T, and C125A; R38A, F42K, N88D, and C125A; R38A, F42K, N88A, and C125A; R38A, F42K, V91E, and C125A; R38A, F42K, D84H, and C125A; R38A, F42K, D84K, and C125A; R38A, F42K, D84R, and C125A; H16D, R38A, F42K, and C125A; H16E, R38A, F42K, and C125A; R38A, F42K, C125A and Q126S; F42A, E62Q, N88S, and C125A; F42A, E62Q, N88A, and C125A; F42A, E62Q, N88G, and C125A; F42A, E62Q, N88R, and C125A; F42A, E62Q, N88T, and C125A; F42A, E62Q, N88D, and C125A; F42A, E62Q, V91E, and C125A; F42A, E62Q, and D84H, and C125A; F42A, E62Q, and D84K, and C125A; F42A, E62Q, and D84R, and C125A; H16D, F42A, and E62Q, and C125A; H16E, F42A, E62Q, and C125A; F42A, E62Q, C125A and Q126S; F42A, N88S, and C125A; F42A, N88A, and C125A; F42A, N88G, and C125A; F42A, N88R, and C125A; F42A, N88T, and C125A; F42A, N88D, and C125A; F42A, V91E, and C125A; F42A, D84H, and C125A; F42A, D84K, and C125A; F42A, D84R, and C125A; H16D, F42A, and C125A; H16E, F42A, and C125A; and F42A, C125A and Q126S. In some embodiments, the IL-2 polypeptide comprises the sequencesequenceWITFAQSIISTLT (SEQ ID NO:297). In some embodiments, the IL-2 polypeptide comprises a sequence selected from the group consisting of SEQ ID Nos: 85-155 and 190-216. In some embodiments, the IL-2 polypeptide comprises a sequence selected from the group consisting of SEQ ID Nos: 80, 85-155, 190-216, 297, and 354-383. In some embodiments, the second moiety comprises a polypeptide that induces signaling via IL2REJ^ In some embodiments, the second moiety comprises an IL-21 polypeptide.

[0023] In some embodiments according to any of the embodiments described herein (e.g., a fusion protein of the present disclosure), one or both of the antibody Fc domains comprise(s) human IgG1 Fc domains with the following amino acid substitutions: L234A, L235A, G237A, and K322A, numbering according to EU index. In some embodiments, one or both of the antibody Fc domains do not have a C-terminal lysine. In some embodiments, one or both of the antibody Fc domains comprise(s) human IgG1 Fc domains with the following amino acid substitutions: L234A, L235A, and G237A, numbering according to EU index. In some embodiments, one or both of the antibody Fc domains do not have a C-terminal lysine. In some embodiments, a first of the two Fc domains comprises a human IgG1 Fc domain with amino acid substitutions Y349C and T366W, and a second of the two Fc domain comprises a human IgG1 Fc domain with amino acid substitutions S354C, T366S, L368A and Y407V, numbering according to EU index. In some embodiments, one or both of the antibody Fc domains do not have a C-terminal lysine. In some embodiments (e.g., a fusion protein of the present disclosure), the linker comprises the sequence (GGGS)xGn (SEQ ID NO:74), (GGGGS)xGn (SEQ ID NO:75), or (GGGGGS)xGn (SEQ ID NO:76), S(GGGS)xGn (SEQ ID NO:386), S(GGGGS)xGn (SEQ ID NO:387), or S(GGGGGS)xGn (SEQ ID NO:388), wherein x=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and wherein n=0, 1, 2 or 3. In some embodiments, the linker comprises the sequence GGGGSGGGGSGGGGS (SEQ ID NO:79) or SGGGGSGGGGSGGGGS (SEQ ID NO:389). In some embodiments (e.g., in a fusion protein of the present disclosure), the linker connects a first moiety of the present disclosure (e.g., a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab) and a second moiety of the present disclosure (e.g., an IL-2 polypeptide of the present disclosure, IL-21 polypeptide of the present disclosure, or a polypeptide that induces signaling via IL2REJ^of the present disclosure).

[0024] In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:158. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:217. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:161. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:218. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:164. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:219. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:167. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:220. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:170. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chaincomprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:221. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:173. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:222. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:176. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:223. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:189. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:224. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:300. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:301. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:304. In some embodiments, a fusionprotein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:305. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:308. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:309. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:312. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:313. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:316. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:317. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:320. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:321. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the aminoacid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:324. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:325. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:328. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:329. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:332. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:333. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:336. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:337. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:340. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:341. In some embodiments, a fusion protein of the presentdisclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:344. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:345. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:348. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:349. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:352. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:217. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:218. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:219. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:220. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chainscomprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:221. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:222. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:223. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:224. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:301. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:305. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:309. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:313. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:317. In some embodiments, a fusion protein of the present disclosure comprisesone or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:321. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:325. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:329. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:333. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:337. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:341. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:345. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:349. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:353. In some embodiments, thefusion protein comprises one or two antigen binding sites, each antigen binding site comprising a VL domain from one of the light chain(s) and a VH domain from one of the heavy chains (e.g., the fusion protein comprises two antigen binding sites: one comprising a VL domain from one of the two light chains and a VH domain from one of the heavy chains, and another comprising a VL domain from the other light chain and a VH domain from the other heavy chain).

[0025] In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:156, a polypeptide comprising the amino acid sequence of SEQ ID NO:157, and a polypeptide comprising the amino acid sequence of SEQ ID NO:158. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:156, a polypeptide comprising the amino acid sequence of SEQ ID NO:157, and a polypeptide comprising the amino acid sequence of SEQ ID NO:217. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:159, a polypeptide comprising the amino acid sequence of SEQ ID NO:160, and a polypeptide comprising the amino acid sequence of SEQ ID NO:161. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:159, a polypeptide comprising the amino acid sequence of SEQ ID NO:160, and a polypeptide comprising the amino acid sequence of SEQ ID NO:218. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:162, a polypeptide comprising the amino acid sequence of SEQ ID NO:163, and a polypeptide comprising the amino acid sequence of SEQ ID NO:164. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:162, a polypeptide comprising the amino acid sequence of SEQ ID NO:163, and a polypeptide comprising the amino acid sequence of SEQ ID NO:219. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:165, a polypeptide comprising the amino acid sequence of SEQ ID NO:166, and a polypeptide comprising the amino acid sequence of SEQ ID NO:167. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:165, a polypeptide comprising the amino acid sequence of SEQ ID NO:166, and a polypeptide comprising the amino acid sequence of SEQ ID NO:220. In someembodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:168, a polypeptide comprising the amino acid sequence of SEQ ID NO:169, and a polypeptide comprising the amino acid sequence of SEQ ID NO:170. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:168, a polypeptide comprising the amino acid sequence of SEQ ID NO:169, and a polypeptide comprising the amino acid sequence of SEQ ID NO:221. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:171, a polypeptide comprising the amino acid sequence of SEQ ID NO:172, and a polypeptide comprising the amino acid sequence of SEQ ID NO:173. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:171, a polypeptide comprising the amino acid sequence of SEQ ID NO:172, and a polypeptide comprising the amino acid sequence of SEQ ID NO:222. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:174, a polypeptide comprising the amino acid sequence of SEQ ID NO:175, and a polypeptide comprising the amino acid sequence of SEQ ID NO:176. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:174, a polypeptide comprising the amino acid sequence of SEQ ID NO:175, and a polypeptide comprising the amino acid sequence of SEQ ID NO:223. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:187, a polypeptide comprising the amino acid sequence of SEQ ID NO:188, and a polypeptide comprising the amino acid sequence of SEQ ID NO:189. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:187, a polypeptide comprising the amino acid sequence of SEQ ID NO:188, and a polypeptide comprising the amino acid sequence of SEQ ID NO:224. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:298, a polypeptide comprising the amino acid sequence of SEQ ID NO:299, and a polypeptide comprising the amino acid sequence of SEQ ID NO:300. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:298, a polypeptidecomprising the amino acid sequence of SEQ ID NO:299, and a polypeptide comprising the amino acid sequence of SEQ ID NO:301. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:302, a polypeptide comprising the amino acid sequence of SEQ ID NO:303, and a polypeptide comprising the amino acid sequence of SEQ ID NO:304. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:302, a polypeptide comprising the amino acid sequence of SEQ ID NO:303, and a polypeptide comprising the amino acid sequence of SEQ ID NO:305. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:306, a polypeptide comprising the amino acid sequence of SEQ ID NO:307, and a polypeptide comprising the amino acid sequence of SEQ ID NO:308. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:306, a polypeptide comprising the amino acid sequence of SEQ ID NO:307, and a polypeptide comprising the amino acid sequence of SEQ ID NO:309. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:310, a polypeptide comprising the amino acid sequence of SEQ ID NO:311, and a polypeptide comprising the amino acid sequence of SEQ ID NO:312. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:310, a polypeptide comprising the amino acid sequence of SEQ ID NO:311, and a polypeptide comprising the amino acid sequence of SEQ ID NO:313. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:314, a polypeptide comprising the amino acid sequence of SEQ ID NO:315, and a polypeptide comprising the amino acid sequence of SEQ ID NO:316. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:314, a polypeptide comprising the amino acid sequence of SEQ ID NO:315, and a polypeptide comprising the amino acid sequence of SEQ ID NO:317. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:318, a polypeptide comprising the amino acid sequence of SEQ ID NO:319, and a polypeptide comprising the amino acid sequence of SEQ ID NO:320. In some embodiments, afusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:318, a polypeptide comprising the amino acid sequence of SEQ ID NO:319, and a polypeptide comprising the amino acid sequence of SEQ ID NO:321. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:322, a polypeptide comprising the amino acid sequence of SEQ ID NO:323, and a polypeptide comprising the amino acid sequence of SEQ ID NO:324. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:322, a polypeptide comprising the amino acid sequence of SEQ ID NO:323, and a polypeptide comprising the amino acid sequence of SEQ ID NO:325. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:326, a polypeptide comprising the amino acid sequence of SEQ ID NO:327, and a polypeptide comprising the amino acid sequence of SEQ ID NO:328. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:326, a polypeptide comprising the amino acid sequence of SEQ ID NO:327, and a polypeptide comprising the amino acid sequence of SEQ ID NO:329. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:330, a polypeptide comprising the amino acid sequence of SEQ ID NO:331, and a polypeptide comprising the amino acid sequence of SEQ ID NO:332. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:330, a polypeptide comprising the amino acid sequence of SEQ ID NO:331, and a polypeptide comprising the amino acid sequence of SEQ ID NO:333. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:334, a polypeptide comprising the amino acid sequence of SEQ ID NO:335, and a polypeptide comprising the amino acid sequence of SEQ ID NO:336. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:334, a polypeptide comprising the amino acid sequence of SEQ ID NO:335, and a polypeptide comprising the amino acid sequence of SEQ ID NO:337. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:338, a polypeptide comprising the aminoacid sequence of SEQ ID NO:339, and a polypeptide comprising the amino acid sequence of SEQ ID NO:340. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:338, a polypeptide comprising the amino acid sequence of SEQ ID NO:339, and a polypeptide comprising the amino acid sequence of SEQ ID NO:341. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:342, a polypeptide comprising the amino acid sequence of SEQ ID NO:343, and a polypeptide comprising the amino acid sequence of SEQ ID NO:344. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:342, a polypeptide comprising the amino acid sequence of SEQ ID NO:343, and a polypeptide comprising the amino acid sequence of SEQ ID NO:345. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:346, a polypeptide comprising the amino acid sequence of SEQ ID NO:347, and a polypeptide comprising the amino acid sequence of SEQ ID NO:348. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:346, a polypeptide comprising the amino acid sequence of SEQ ID NO:347, and a polypeptide comprising the amino acid sequence of SEQ ID NO:349. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:350, a polypeptide comprising the amino acid sequence of SEQ ID NO:351, and a polypeptide comprising the amino acid sequence of SEQ ID NO:352. In some embodiments, a fusion protein of the present disclosure comprises one or two polypeptides comprising the amino acid sequence of SEQ ID NO:350, a polypeptide comprising the amino acid sequence of SEQ ID NO:351, and a polypeptide comprising the amino acid sequence of SEQ ID NO:353.

[0026] Further provided herein are fusion proteins, comprising a first moiety that binds to a human CD8b and a second moiety comprising an IL2 polypeptide, wherein the fusion protein comprises four polypeptide chains, wherein: (1) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:336, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; (2) the first polypeptide chain comprises the amino acid sequence of SEQ IDNO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:337, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; (3) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:340, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:338; or (4) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:341, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:338.

[0027] Further provided herein are polynucleotides (e.g., isolated polynucleotides) encoding the antibody or fusion protein according to any one of the above embodiments. Further provided herein are vectors (e.g., expression vectors) comprising the polynucleotide(s) according to any one of the above embodiments. Further provided herein are host cells (e.g., isolated host cells or cell lines) comprising the polynucleotide(s) or vector(s) according to any one of the above embodiments. Further provided herein are methods of producing an antibody or fusion protein, comprising culturing the host cell according to any one of the above embodiments under conditions suitable for production of the antibody or fusion protein. In some embodiments, the methods further comprise recovering the antibody or fusion protein from the host cell.

[0028] Further provided herein are pharmaceutical compositions comprising the antibody or fusion protein according to any one of the above embodiments and a pharmaceutically acceptable carrier.

[0029] Further provided herein is the use of the antibody, fusion protein, or composition according to any one of the above embodiments as a medicament. Further provided herein is the use of the antibody, fusion protein, or composition according to any one of the above embodiments in a method for treating cancer or infection (e.g., chronic infection). Further provided herein is the use of the antibody, fusion protein, or composition according to any one of the above embodiments for the manufacture of a medicament for treating cancer or infection (e.g., chronic infection). Further provided herein are methods of treating cancer comprisingadministering to an individual with cancer an effective amount of the antibody, fusion protein, or composition according to any one of the above embodiments. In some embodiments, the methods further comprise administering to the individual a T cell therapy, cancer vaccine, chemotherapeutic agent, or immune checkpoint inhibitor (ICI). Further provided herein are methods of treating infection (e.g., chronic infection) comprising administering to an individual with infection an effective amount of the antibody, fusion protein, or composition according to any one of the above embodiments. Further provided herein are methods of expanding T cells (e.g., ex vivo) comprising contacting one or more T cells (e.g., tumor infiltrating lymphocytes) ex vivo (e.g., ex vivo) with an effective amount of the antibody, fusion protein, or composition according to any one of the above embodiments.

[0030] It is to be understood that one, some, or all of the properties of the various embodiments described herein may be combined to form other embodiments of the present disclosure. These and other aspects of the disclosure will become apparent to one of skill in the art. These and other embodiments of the disclosure are further described by the detailed description that follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIGS.1A-1C depict the three types of CD8ab antibodies that could be identified according to their binding preference for CD8a, CD8b and CD8ab heterodimer. Antibodies binding CD8a epitopes are shown in FIG.1A, antibodies binding epitopes that span both CD8a and CD8b are shown in FIG. 1B, and antibodies binding to CD8b epitopes are shown in FIG. 1C. Binding preference for CD8a, CD8b and CD8ab heterodimer by each antibody type is also depicted.

[0032] FIGS.2A-2C show the results of an ELISA assay used to distinguish the three types of CD8ab antibodies depicted in FIGS.1A-1C. Binding to recombinant CD8a (filled square), CD8b (filled triangle), CD8ab heterodimer (filled circle) and an irrelevant antigen, ovalbumin (open triangles) was measured. xhCD8a1 (clone OKT8) and xhCD8a2 antibodies (clone SK1) were previously described.

[0033] FIGS.3A-3C depict the binding preferences on various CD8+ immune cell types by the three types of anti-CD8ab antibodies depicted in FIGS. 2A-2C. Antibodies with CD8a epitopes depicted in FIG 1A bind to both CD8ab+ T cells and CD8aa+ NK cells as depicted inFIG.3A. Antibodies with epitopes that span both CD8a and CD8b depicted in FIG. 1B preferentially bind to CD8ab+ T cells over CD8aa+ NK cells as depicted in FIG. 3B. Antibodies with CD8b epitopes depicted in FIG.1C preferentially bind to CD8ab+ T cells over CD8aa+ NK cells as depicted in FIG. 3C.

[0034] FIGS.4 & 5 depict the results of a flow cytometry assay to detect the binding of CD8ab antibodies to human PBMCs and distinguish the three types of CD8ab antibodies depicted in FIGS.1A-1C. Binding of CD8ab antibodies to T cells (FIG.4) and NK cells (FIG. 5) in hPBMCs was detected by staining with anti-human Fc antibody conjugated to APC. Anti- hFc was used to measure the binding of CD8 antibodies containing hFc. Mean fluorescence intensity (MFI) of staining with anti-hFc is used to denote binding. Binding of anti-hFc was determined in CD3+CD8a+CD8b+cells (CD8+ T cells) and CD3-CD56+CD8a+ cells (CD8+ NK cells).

[0035] FIG.6 depicts the results of a flow cytometry assay measuring the binding of CD8ab antibodies binding CD8b epitopes, xhCD8v1 to xhCD8v5, to CD8+ T cells. Negative control antibody, binding HA antigen, was also included.

[0036] FIG.7 depicts four different formats (formats A, B, C, and D) of fusion proteins comprising CD8ab antibodies of the present disclosure, in accordance with some embodiments.

[0037] FIGS.8A-8C depict fusion proteins comprising the three types of CD8ab antibodies depicted in FIGS.1A-1C and FIGS. 3A-3C and an IL-2Rbg-binding polypeptide. Preferential activation of CD8ab+ T cells over CD8aa+ NK cells is shown.

[0038] FIG.9 shows the results of an assay to determine the selectivity of fusion proteins comprising the CD8ab antibodies and an IL-2Rbg-binding polypeptide, IL2m1. The expression of the proliferation marker Ki-67 in CD8+ T cells and NK cells from a hPBMC donor was measured by flow cytometry after five days of co-culture with the following fusion proteins: Ctrl Ab-IL2v, comprising a control antibody and a previously published IL-2 variant (Klein et al, Oncoimmunol.2017; 6(3); e1277306) (top panel); xhCD8a1-IL-2m1, comprising CD8 antibody, xhCD8a1, targeting CD8a epitope, and the mutant IL-2 polypeptide of the present disclosure, IL2m1 (bottom left panel); and xhCD8v1-IL2m1, comprising CD8ab antibody of the present disclosure, xhCD8v1, and IL2m1 (bottom right panel). xhCD8a1-IL-2m1 was of format C, while Ctrl Ab-IL2v and xhCD8v1-IL2m1 were of format A Ki-67 expression was measured in CD8+T cells (filled circles) and NK cells (filled squares). NK cells were defined as CD3-CD56+. CD8 expression was measured by staining with CD8 antibody SK1.

[0039] FIGS.10A-10C depict the expression of Ki-67 proliferation marker after five day co- culture of hPBMCs from three different donors with indicated fusion proteins. All fusion proteins contained the mutant IL-2 polypeptide, IL2m1, and CD8ab antibodies of the present disclosure, xhCD8v1 to xhCD8v7 and were of format A. Ki-67 expression was measured in CD8+ T cells (solid lines) and NK cells (dashed lines).

[0040] FIGS.11A-11D show the results of the phospho-STAT5 assay with hPBMCs from one donor cultured with the indicated fusion proteins, all of format C. Percent pSTAT5- expressing cells was depicted in the following hPBMC subsets: CD8+ T cells (FIG. 11A), NK cells (FIG.11B), Treg cells (FIG. 11C), and CD4+Foxp3- T cells (FIG.11D). NK cells were identified as CD3-Perforin+. Treg cells were identified as CD4+Foxp3+CD25+.

[0041] FIG.12 shows the expression of Ki-67 proliferation marker after five day co-culture of hPBMCs from one donor with indicated fusion proteins. All fusion proteins contained the CD8ab antibody of the present disclosure, xhCD8v1, and various mutant IL-2 polypeptides of the present disclosure, IL2m1 to IL2m5, and were of format A. Ki-67 expression was measured in CD8+ T cells (left panel) and NK cells (right panel).

[0042] FIG.13A and FIG.13B show the results of the phospho-STAT5 assay with hPBMCs from one donor cultured with the indicated fusion proteins. Percent pSTAT5-expressing cells was depicted in the following hPBMC subsets: CD8+ T cells and NK cells. In FIG.13A, all fusion proteins contained the CD8ab antibody of the present disclosure, xhCD8v1, and various mutant IL-2 polypeptides of the present disclosure, IL2m1, IL2m2, and IL2m6 to IL2m10, and were of format A. In FIG.13B, fusion proteins contained the CD8ab antibodies of the present disclosure, xhCD8v11 and xhCD8v12, and various mutant IL-2 polypeptides of the present disclosure, IL2m11, IL2m12, and IL2m13, and were of format A. NK cells were identified as CD3-Perforin+.

[0043] FIG.14A shows the expression of Ki-67 proliferation marker after five day co- culture of hPBMCs from one donor with xhCD8v1-IL2m1 (left panel) and xhCD8v6-IL2m1 (right panel). Three different fusion protein formats as depicted in FIG.7 were tested: format A, format B and format C as indicated Solid lines depict Ki-67 expression in CD8+ T cells anddashed lines represent Ki-67 expression in NK cells. Format A resulted in substantial increase in activity on CD8+ T cells over NK cells for both CD8ab antibodies tested suggesting this is the preferred format for fusion proteins containing CD8ab antibodies targeting epitopes between CD8a and CD8b (FIG.8B) or CD8b epitopes (FIG.8C). FIG. 14B depicts the binding (left panel) and induction of Ki67 (right panel) in CD8+ T cells from one donor with xhCD8v6- IL2m1. Four different fusion protein formats as depicted in FIG. 7 were tested: format A, format B, format C, and format D as indicated. While format A is approximately 5-fold stronger than other format in cell binding, format A is 20- to 40-fold more potent than other formats in inducing Ki-67. FIG. 14C depicts the results of nine fusion molecules in format A and D as assessed for binding to CD8+ T cells, and induction of Ki67 in CD8+ T cells. Examples for binding and ki-67 curves for xhCD8v12-IL2m4 were shown in the left panel. For a given binder and mutein pair, the ratio of EC50s of format D over format A is shown for binding and Ki67 in the right panel. For all the molecules tested, format A showed a potency shift over format D of approximately 10-fold in binding EC50. However, when assessed for the activation of a further downstream proliferation marker Ki67, format A exhibits approximately 1000-fold increase in potency over format D in inducing Ki-67.

[0044] FIG.15 shows the expression of Ki-67 proliferation marker after five day co-culture of hPBMCs with xhCD8v8-IL2m1, a fusion protein of format A containing the mutant IL-2 polypeptide, IL2m1, and CD8ab antibody of the present disclosure, xhCD8v8. Ki-67 expression was measured in CD8+ T cells (squares) and NK cells (triangles).

[0045] FIG.16A depicts the expression of Ki-67 in tumor infiltrating lymphocytes (TILs) gated on CD8+ T cells (left panel) and NK cells (right panel). TILs were incubated with rhIL-2 or the indicated fusion proteins (format A) for five days before analysis. FIG.16B depicts the number of CD8+ T cells, NK cells, and CD4+ T cells per well in each of the indicated conditions.

[0046] FIGS.17A-17E show expression of Ki-67 proliferation marker after five day co- culture of hPBMCs with fusion proteins of format A containing a mutant IL-2 polypeptide (IL2m1 or IL2m4) and an CD8ab antibody of the present disclosure. CD8ab antibodies xhCD8v9-14 were tested. Ki-67 expression was measured in CD8+ T cells (squares) and NK cells (triangles).

[0047] FIG.18A shows numbers of amino acid liabilities (e.g., putative N-linked glycosylation, deamination, or acid cleavage sites) and amino acid mismatches as compared to human germline of the indicated anti-CD8ab antibodies.

[0048] FIG.18B shows alignments illustrating how CDRs (italics) from xhCD8v1 VH (top) and VK (bottom) were grafted onto VH1-69 and VK1-39 human germline frameworks, respectively. VH domain sequences (top) correspond to SEQ ID Nos: 58, 384, and 60, respectively (top to bottom). VL domain sequences (bottom) correspond to SEQ ID Nos: 59, 385, and 61, respectively (top to bottom). Underlined residues depict framework residues of human germline.

[0049] FIGS.18C & 18D show alignments of VH (FIG. 18C) and VL (FIG.18D) domains of the indicated anti-CD8ab antibodies of the present disclosure. VH domain sequences (FIG. 18C) correspond to SEQ ID Nos: 60, 62, 64, 66, 68, 245, 251, and 253, respectively (top to bottom). VL domain sequences (FIG. 18D) correspond to SEQ ID Nos: 61, 63, 65, 67, 69, 246, 252, and 254, respectively (top to bottom).

[0050] FIG.19 shows the results of an ELISA assay used to identify glycosylation of the parental xhCD8v6 (black solid line with black squares), which is removed upon treatment with glycosidases (black dashed line with black squares). No glycosylation is detected on the xhCD8v11 (gray lines with open triangles). Fetuin is shown as a positive control. DETAILED DESCRIPTION Definitions

[0051] As used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a molecule” optionally includes a combination of two or more such molecules, and the like.

[0052] It is understood that aspects and embodiments of the present disclosure include “comprising,” “consisting,” and “consisting essentially of” aspects and embodiments.

[0053] The term “about” as used herein refers to the usual error range for the respective value readily known to the skilled person in this technical field. Reference to “about” a value orparameter herein includes (and describes) embodiments that are directed to that value or parameter per se.

[0054] “Immune cells” as used here are cells of the immune system that react to organisms or other entities that are deemed foreign to the immune system of the host. They protect the host against foreign pathogens, organisms and diseases. Immune cells, also called leukocytes, are involved in both innate and adaptive and immune responses to fight pathogens. Innate immune responses occur immediately upon exposure to pathogens without additional priming or learning processes. Adaptive immune processes require initial priming, and subsequently create memory, which in turn leads to enhanced responsiveness during subsequent encounters with the same pathogen. Innate immune cells include, but are not limited to monocytes, macrophages, dendritic cells, innate lymphoid cells (ILCs) including natural killer (NK) cells, neutrophils, megakaryocytes, eosinophils and basophils. Adaptive immune cells include B and T lymphocytes / cells. T cells subsets include, but are not limited to, alpha beta CD4+ T (naïve CD4+, memory CD4+, effector memory CD4+, effector CD4+, regulatory CD4+), and alpha beta CD8+ T (naïve CD8+, memory CD8+, effector memory CD8+, effector CD8+). B cell subsets include, but is not limited to, naïve B, memory B, and plasma cells. NK T cells and T gamma delta (TJG) cells exhibit properties of both innate and adaptive lymphocytes.

[0055] “T cells” or “T lymphocytes” are immune cells that play a key role in the orchestration of immune responses in health and disease. Two major T cell subsets exist that have unique functions and properties: T cells that express the CD8 antigen (CD8+T cells) are cytotoxic or killer T cells that can lyse target cells using the cytotoxic proteins such as granzymes and perforin; and T cells that express the CD4 antigen (CD4+T cells) are helper T cells that are capable of regulating the function of many other immune cell types including that of CD8+T cells, B cells, macrophages etc. Furthermore, CD4+T cells are further subdivided into several subsets such as: T regulatory (Treg) cells that are capable of suppressing the immune response, and T helper 1 (Th1), T helper 2 (Th2), and T helper 17 (Th17) cells that regulate different types of immune responses by secreting immunomodulatory proteins such as cytokines. T cells recognize their targets via alpha beta T cell receptors that bind to unique antigen-specific motifs and this recognition mechanism is generally required in order to trigger their cytotoxic and cytokine-secreting functions. “Innate lymphocytes” can also exhibit properties of CD8+andCD4+T cells, such as the cytotoxic activity or the secretion of Th1, Th2, and Th17 cytokines. Some of these innate lymphocyte subsets include NK cells and ILC1, ILC2, and ILC3 cells; and innate-like T cells such as TJG cells; and NK T cells. Typically, these cells can rapidly respond to inflammatory stimuli from infected or injured tissues, such as immunomodulatory cytokines, but unlike alpha beta T cells, they can respond without the need to recognize antigen-specific patterns.

[0056] “Cytokine” is a form of immunomodulatory polypeptide that mediates cross-talk between initiating / primary cells and target / effector cells. It can function as a soluble form or cell- surface associated to bind the “cytokine receptor” on target immune cells to activate signaling. “Cytokine receptor” as used here is the polypeptide on the cell surface that activates intracellular signaling upon binding the cytokine on the extracellular cell surface. Cytokines includes, but are not limited to, chemokines, interferons, interleukins, lymphokines, and tumor necrosis factors. Cytokines are produced by a wide range of cells, including immune cells, endothelial cells, fibroblasts, and stromal cells. A given cytokine may be produced by more than one cell type. Cytokine are pleiotropic; since the receptors are expressed on multiple immune cell subsets, one cytokine can activate the signaling pathway in multiple cells. However, depending on the cell type, the signaling events for a cytokine can result in different downstream cellular events such as activation, proliferation, survival, apoptosis, effector function and secretion of other immunomodulatory proteins.

[0057] “Amino acid” as used here refers to naturally occurring carboxy Į-amino acids comprising alanine (three letter code: ala, one letter code: A), arginine (arg, R), asparagine (asn, N), aspartic acid (asp, D), cysteine (cys, C), glutamine (gln, Q), glutamic acid (glu, E), glycine (gly, G), histidine (his, H), isoleucine (ile, I), leucine (leu, L), lysine (lys, K), methionine (met, M), phenylalanine (phe, F), proline (pro, P), serine (ser, S), threonine (thr, T), tryptophan (trp, W), tyrosine (tyr, Y), and valine (val, V).

[0058] "Polypeptide" or “protein” as used here refers to a molecule where monomers (amino acids) are linearly linked to one another by peptide bonds (also known as amide bonds). The term "polypeptide" refers to any chain of two or more amino acids and does not refer to a specific length of the product. Thus, peptides, dipeptides, tripeptides, oligopeptides, "protein", "amino acid chain", or any other term used to refer to a chain of two or more amino acids, areincluded within the definition of "polypeptide", and the term "polypeptide" may be used instead of, or interchangeably with any of these terms. The term "polypeptide" is also intended to refer to the products of A polypeptide may be derived from a natural biological source or produced by recombinant technology but is not necessarily translated from a designated nucleic acid sequence. It may be generated in any manner, including by chemical synthesis. Polypeptides normally have a defined three-dimensional structure, but they do not necessarily have such structure. A polypeptide of the present^disclosure may be of a size of about 3 or more, 5 or more, 10 or more, 20 or more, 25 or more, 50 or more, 75 or more, 100 or more, 200 or more, 500 or more, 1,000 or more, or 2,000 or more amino acids. Polypeptides with a defined three- dimensional structure are referred to as folded, and polypeptides which do not possess a defined three- dimensional structure, but rather can adopt many different conformations and are referred to as unfolded. Polypeptides may further form multimers such as dimers, trimers and higher oligomers, i.e. consisting of more than one polypeptide molecule. Polypeptide molecules forming such dimers, trimers etc. may be identical or non-identical. The corresponding higher order structures of such multimers are, consequently, termed homo- or heterodimers, homo- or heterotrimers etc. The terms "polypeptide" and "protein" also refer to modified polypeptides / proteins wherein the post-expression modification is affected including without limitation glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting / blocking groups, proteolytic cleavage, or modification by non-naturally occurring amino acids.

[0059] “Residue” as used herein is meant a position in a protein and its associated amino acid identity. For example, Leu 234 (also referred to as Leu234 or L234) is a residue at position 234 in the human antibody IgG1.

[0060] “Wild-type" herein means an amino acid sequence or a nucleotide sequence that is found in nature, including allelic variations. A wild-type protein has an amino acid sequence or a nucleotide sequence that has not been intentionally modified.

[0061] "Substitution” or “mutation” refers to a change to the polypeptide backbone wherein an amino acid occurring naturally in the wild-type sequence of a polypeptide is substituted to another amino acid not naturally occurring at the same position in the said polypeptide. Preferably, a mutation or mutations are introduced to modify polypeptide’s affinity to its receptorthereby altering its activity such that it becomes different from the affinity and activity of the wild-type cognate polypeptide. Mutations can also improve polypeptide’s biophysical properties. Amino acid mutations can be generated using genetic or chemical methods well known in the art. Genetic methods may include site-directed mutagenesis, PCR, gene synthesis and the like. It is contemplated that methods of altering the side chain group of an amino acid by methods other than genetic engineering, such as chemical modification, may also be useful.

[0062] "CD8" as used here refers to any native human CD8. Unless otherwise indicated expressly or by context, references to “CD8” refer to CD8aa and / or CD8ab. The amino acid sequence of an exemplary human CD8b, the beta chain of human CD8, is described under UniProt P10966 (CD8B_HUMAN). “CD8a” refers to the alpha chain of human CD8 (e.g., as is described under UniProt P01732 (CD8A_HUMAN)). “CD8aa” refers to a homodimer of CD8a. “CD8ab” refers to a heterodimer of CD8a and CD8b. "CD8," “CD8a,” “CD8b,” “CD8aa,” and “CD8ab” encompass unprocessed forms as well as mature forms that result from processing in the cell. "CD8," “CD8a,” “CD8b,” “CD8aa,” and “CD8ab” also include but are not limited to naturally occurring variants, e.g. allelic or splice variants or variants.

[0063] "Interleukin-2" or "IL-2" as used here refers to any native human IL-2, unless otherwise indicated. "IL-2" encompasses unprocessed IL-2 as well as “mature IL-2” which is a form of IL-2 that results from processing in the cell. The sequence of “mature IL-2” is depicted in Fig 1A. One exemplary form of unprocessed human IL-2 comprises of an additional N- terminal amino acid signal peptide attached to mature IL-2."IL-2" also includes but is not limited to naturally occurring variants of IL-2, e.g. allelic or splice variants or variants. The amino acid sequence of an exemplary human IL-2 is described under UniProt P60568 (IL2_HUMAN).

[0064] "Affinity" or "binding affinity" refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g. an antibody) and its binding partner (e.g. an antigen). Unless indicated otherwise, as used herein, "binding affinity" refers to intrinsic binding affinity which reflects a 1:1 interaction between members of a binding pair (e.g. antibody and antigen). The affinity can generally be represented by the dissociation constant (KD), which is the ratio of dissociation and association rate constants (koff and kon, respectively). Thus, equivalent affinities may comprise different rate constants, as long as the ratio of the rate constants remains the same. Affinity can be measured by common methodsknown in the art, such as enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR) technologies (e.g. BIAcore), BioLayer Interferometry (BLI) technologies (e.g. Octet) and other traditional binding assays (Heeley, Endocr Res 28, 217-229 (2002).

[0065] “Binding” or "specific binding" as used here, refers the ability of a polypeptide or an antigen binding molecule to selectively interact with the receptor for the polypeptide or target antigen, respectively, and this specific interaction can be distinguished from non-targeted or undesired or non-specific interactions. Examples of specific binding include but are not limited to IL-2 cytokine binding to its specific receptors (e.g. IL-2RD, IL-2RE and IL-2RJ) and an antigen binding molecule binding to a specific antigen (e.g. CD8 or PD-1).

[0066] “Mutant IL-2 polypeptide” refers to IL-2 polypeptide that has reduced affinity to its receptor wherein such decreased affinity will result in reduced biological activity of the mutant. Reduction in affinity and thereby activity can be obtained by introducing a small number of amino acid mutations or substitutions. The mutant IL-2 polypeptides can also have other modifications to the peptide backbone, including but not limited to amino acid deletion, permutation, cyclization, disulfide bonds, or the post-translational modifications (e.g. glycosylation or altered carbohydrate) of a polypeptide, chemical or enzymatic modifications to the polypeptide (e.g. attaching PEG to the polypeptide backbone), addition of peptide tags or labels, or fusion to proteins or protein domains to generate a final construct with desired characteristics, such as reduced affinity to IL-2RȕȖ. Desired activity may also include improved biophysical properties compared to the wild-type IL-2 polypeptide. Multiple modifications may be combined to achieve desired activity modification, such as reduction in affinity or improved biophysical properties. As a non-limiting example, amino acid sequences for consensus N-link glycosylation may be incorporated into the polypeptide to allow for glycosylation. Another non- limiting example is that a lysine may be incorporated onto the polypeptide to enable pegylation. Preferably, a mutation or mutations are introduced to the polypeptide to modify its activity.

[0067] The terms "antibody" and “immunoglobulin” are used interchangeably and herein are used in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies (e.g., full length or intact monoclonal antibodies), polyclonal antibodies, multispecific antibodies (e.g. bispecific antibodies), antibody fragments and singledomain antibody (as described in greater detail herein), so long as they exhibit the desired antigen binding activity.

[0068] Antibodies (immunoglobulins) refer to a protein having a structure substantially similar to a native antibody structure. “Native antibodies” refer to naturally occurring immunoglobulin molecules with varying structures. For example, native immunoglobulins of the IgG class are heterotetrameric glycoproteins of about 150,000 daltons, composed of two light chains and two heavy chains that are disulfide-bonded. From N- to C-terminus, each heavy chain has a variable region (VH), also called a variable heavy domain or a heavy chain variable domain, followed by three constant domains (CH1, CH2, and CH3), also called a heavy chain constant region. Similarly, from N- to C-terminus, each light chain has a variable region (VL), also called a variable light domain or a light chain variable domain, followed by a constant light (CL) domain, also called a light chain constant region. The subunit structures and three- dimensional configurations of the different classes of immunoglobulins are well known and described generally, for example, in Abbas et al., 2000, Cellular and Mol, and Kindt et al., Kuby Immunology, 6th ed., W.H. Freeman and Co., page 91 (2007). Antibodies (immunoglobulins) are assigned to different classes, depending on the amino acid sequences of the heavy chain constant domains. There are five major classes of antibodies: Į (IgA), į (IgD), ^ (IgE), Ȗ (IgG), or ^ (IgM), some of which may be further divided into subtypes, e.g. Ȗ1 (IgG1), Ȗ2 (IgG2), Ȗ3 (IgG3), Ȗ4 (IgG4), Į1 (IgA1) and Į2 (IgA2). The light chain of an immunoglobulin may be assigned to one of two types, called kappa (^) and lambda (^), based on the amino acid sequence of its constant domain. An immunoglobulin essentially consists of two Fab molecules and an Fc domain, linked via the immunoglobulin hinge region.

[0069] “Fc” or “Fc region” or “Fc domain” as used herein refers to the C-terminal region of an antibody heavy chain that contains at least a portion of the constant region. The term includes native sequence Fc regions and variant Fc regions. An Fc can refer to the last two constant region immunoglobulin domains (e.g., CH2 and CH3) of IgA, IgD, and IgG, the last three constant region immunoglobulin domains of IgE and IgM, and optionally, all or a portion of the flexible hinge N-terminal to these domains. For IgA and IgM, Fc may include the J chain. An IgG Fc region comprises an IgG CH2 and an IgG CH3 domain and in some cases, inclusive of the hinge. Unless otherwise specified herein, numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system also called the EU index as described in Kabatet al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md., 1991. The “hinge” region usually extends from amino acid residue at about position 216 to amino acid residue at about position 230. The hinge region herein may be a native hinge domain or variant hinge domain. The “CH2 domain” of a human IgG Fc region usually extends from an amino acid residue at about position 231 to an amino acid residue at about position 340. The CH2 domain herein may be a native sequence CH2 domain or variant CH2 domain. The “CH3 domain” comprises the stretch of residues C-terminal to a CH2 domain in an Fc region, from an amino acid residue at about position 341 to an amino acid residue at about position 447 of an IgG. The CH3 region herein may be a native sequence CH3 domain or a variant CH3 domain (e.g. a CH3 domain with an introduced “protuberance” (“knob”) in one chain thereof and a corresponding introduced “cavity” (“hole”) in the other chain thereof; see U.S. Pat. No.5,821,333, expressly incorporated herein by reference). Thus, the definition of “Fc domain” includes both amino acids 231-447 (CH2-CH3) or 216-447 (hinge- CH2-CH3), or fragments thereof. An “Fc fragment” in this context may contain fewer amino acids from either or both of the N- and C-termini but still retains the ability to form a dimer with another Fc domain or Fc fragment as can be detected using standard methods, generally based on size (e.g. non-denaturing chromatography, size exclusion chromatography, etc.). Human IgG Fc domains are of particular use in the present disclosure, and can be the Fc domain from human IgG1, IgG2 or IgG4.

[0070] A “variant Fc domain” or “Fc variant” or “variant Fc” contains amino acid modifications (e.g. substitution, addition, and deletion) as compared to a parental Fc domain. The term also includes naturally occurring allelic variants of the Fc region of an immunoglobulin. In general, variant Fc domains have at least about 80, 85, 90, 95, 97, 98 or 99 percent identity to the corresponding parental human IgG Fc domain (using the identity algorithms discussed below, with one embodiment utilizing the BLAST algorithm as is known in the art, using default parameters). Alternatively, the variant Fc domains can have from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 amino acid modifications as compared to the parental Fc domain. For example, one or more amino acids can be deleted from the N-terminus or C-terminus of the Fc region of an immunoglobulin without substantial loss of biological function. Additionally, as discussed herein, the variant Fc domains herein still retainthe ability to form a dimer with another Fc domain as measured using known techniques as described herein, such as non-denaturing gel electrophoresis.

[0071] “Fc gamma receptor”, “FcȖR” or “Fc gamma R” as used herein is meant any member of the family of proteins that bind the IgG antibody Fc region and is encoded by an FcȖR gene. In humans this family includes but is not limited to FcȖRI (CD64), including isoforms FcȖRIa, FcȖRIb, and FcȖRIc; FcȖRII (CD32), including isoforms FcȖRIIa (including allotypes H131 and R131), FcȖRIIb (including FcȖRIIb-1 and FcȖRIIb-2), and FcȖRIIc; and FcȖRIII (CD16), including isoforms FcȖRIIIa (including allotypes V158 and F158) and FcȖRIIIb (including allotypes FcȖRIIb-NA1 and FcȖRIIb-NA2) (Jefferis et al., 2002, Immunol Lett 82:57-65, entirely incorporated by reference), as well as any undiscovered human FcȖRs or FcȖR isoforms or allotypes. An FcȖR may be from any organism, including but not limited to humans, mice, rats, rabbits, and monkeys. Mouse FcȖRs include but are not limited to FcȖRI (CD64), FcȖRII (CD32), FcȖRIII (CD16), and FcȖRIII-2 (CD16-2), as well as any undiscovered mouse FcȖRs or FcȖR isoforms or allotypes.

[0072] By “effector function” as used herein is meant a biochemical event that results from the interaction of an antibody Fc region with an Fc receptor or ligand, which vary with the antibody isotype. Effector functions include but are not limited to antibody-dependent cell- mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), complement-dependent cytotoxicity (CDC), cytokine secretion, immune complex-mediated antigen uptake by antigen presenting cells, down regulation of cell surface receptors (e.g. B cell receptor), and B cell activation. “Antibody-dependent cell-mediated cytotoxicity” or “ADCC” refer to a cell-mediated reaction in which nonspecific cytotoxic cells that express FcRs (such as Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell. ADCC is correlated with binding to FcȖRIIIa; increased binding to FcȖRIIIa leads to an increase in ADCC activity. To assess ADCC activity of a molecule of interest, an in vitro ADCC assay such as that described in U.S. Pat. No.5,500,362 or 5,821,337 may be performed. “ADCP” or antibody dependent cell-mediated phagocytosis as used herein is meant the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcȖRs recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell.

[0073] “Fc null” and “Fc null variant” are used interchangeably and used herein to describe a modified Fc which have reduced or abolished effector functions. Such Fc null or Fc null variant have reduced or abolished to FcȖRs and / or complement receptors. Preferably, such Fc null or Fc null variant has abolished effector functions. Exemplary methods for the modification include but not limited to chemical alteration, amino acid residue substitution, insertion and deletions. Exemplary amino acid positions on Fc molecules where one or more modifications were introduced to decrease effector function of the resulting variant (numbering based on the EU numbering scheme) at position i) IgG1: C220, C226, C229, E233, L234, L235, G237, P238, S239 D265, S267, N297, L328, P331, K322, A327 and P329, ii) IgG2: V234, G237, D265, H268, N297, V309, A330, A331, K322 and iii) IgG4: L235, G237, D265 and E318. Exemplary Fc molecules having decreased effector function include those having one or more of the following substitutions: i) IgG1: N297A, N297Q, N297G, D265A / N297A, D265A / N297Q, C220S / C226S / C229S / P238S, S267E / L328F, C226S / C229S / E233P / L234V / L235A,

[0074] “Epitope” as used herein refers to a determinant capable of specific binding to the variable region of an antibody molecule known as a paratope. Epitopes are groupings of molecules such as amino acids or sugar side chains and usually have specific structural characteristics, as well as specific charge characteristics. A single antigen may have more than one epitope. The epitope may comprise amino acid residues directly involved in the binding and other amino acid residues, which are not directly involved in the binding, such as amino acid residues which are effectively blocked by the antigen binding peptide (in other words, the amino acid residue is within the footprint of the antigen binding peptide). Epitopes may be either conformational or linear. An epitope typically includes at least 3, and more usually, at least 5 or8-10 amino acids. Antibodies that recognize the same epitope can be verified in a simple immunoassay showing the ability of one antibody to block the binding of another antibody to a target antigen, for example "binning".

[0075] “Linker” as used herein refers to a molecule that connect two polypeptide chains. Linker can be a polypeptide linker or a synthetic chemical linker (for example, see disclosed in Protein Engineering, 9(3), 299-305, 1996). The length and sequence of the polypeptide linkers is not particularly limited and can be selected according to the purpose by those skilled in the art. Polypeptide linker comprises one or more amino acids. In some embodiments, the polypeptide linker is a peptide with a length of at least 5 amino acids, preferably with a length of 5 to 100, more preferably of 10 to 50 amino acids. In one embodiment, said peptide linker is G, S, GS, SG, SGG, GGS, and GSG (with G=glycine and S=serine). In another embodiment, said peptide linker is (GGGS)xGn (SEQ ID NO:74) or (GGGGS)xGn (SEQ ID NO:75) or (GGGGGS)xGn (SEQ ID NO:76) or S(GGGS)xGn (SEQ ID NO:386) or S(GGGGS)xGn (SEQ ID NO:387) or S(GGGGGS)xGn (SEQ ID NO:388), with x=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 and n=0, 1, 2 or 3. Preferably, the said linker is (GGGGS)xGn with x=2,3, or 4 and n=0 (SEQ ID NO:77); more preferably the said linker is (GGGGS)xGn with x=3 and n=0 (SEQ ID NO:78). In some embodiments, the linker comprises the sequence GGGGSGGGGSGGGGS (SEQ ID NO:79) or or SGGGGSGGGGSGGGGS (SEQ ID NO:389). Synthetic chemical linkers include crosslinking agents that are routinely used to crosslink peptides, for example, N-hydroxy succinimide (NHS), disuccinimidyl suberate (DSS), bis(succinimidyl) suberate (BS3), dithiobis(succinimidyl propionate) (DSP), dithiobis(succinimidyl propionate) (DTSSP), ethylene glycol bis(succinimidyl succinate) (EGS), ethylene glycol bis(sulfosuccinimidyl succinate) (sulfo-EGS), disuccinimidyl tartrate (DST), disulfosuccinimidyl tartrate (sulfo-DST), bis[2- (succinimidoxycarbonyloxy)ethyl] sulfone (BSOCOES), and bis[2- (succinimidoxycarbonyloxy)ethyl] sulfone (sulfo-BSOCOES).

[0076] The term "polynucleotide" refers to an isolated nucleic acid molecule or construct, e.g. messenger RNA (mRNA), virally-derived RNA, or plasmid DNA (pDNA) encoding the polypeptides of the present^disclosure. A polynucleotide may comprise a conventional phosphodiester bond or a non-conventional bond (e.g. an amide bond, such as found in peptide nucleic acids (PNA). The term "nucleic acid molecule" refers to any one or more nucleic acidsegments, e.g. DNA or RNA fragments, present in a polynucleotide. In some aspects, one or more vectors (particularly expression vectors) comprising such nucleic acids are provided. In one aspect, a method for making a polypeptide of the present^disclosure is provided, wherein the methods comprises culturing a host cell comprising a nucleic acid encoding the polypeptide under conditions suitable for expression of the polypeptide and recovering the polypeptide from the host cell. "Recombinant" means the proteins are generated using recombinant nucleic acid techniques in exogeneous host cells. Recombinantly produced proteins expressed in host cells are considered isolated for the purpose of the present^disclosure, as are native or recombinant proteins which have been separated, fractionated, or partially or substantially purified by any suitable technique.

[0077] "Isolated," when used to describe the various polypeptides disclosed herein, means a polypeptide that has been identified and separated and / or recovered from a cell or cell culture from which it was expressed. Typically, an isolated polypeptide will be purified by at least one purification step. There is no required level of purity; “purification” or “purified” refers to increase of the target protein concentration relative to the concentration of contaminants in a composition as compared to the starting material. An "isolated protein," as used herein refers to a target protein which is substantially free of other proteins having different binding specificities.

[0078] The terms “cancer” refers the physiological condition in mammals that is typically characterized by unregulated and abnormal cell growth with the potential to invade or spread to other parts of the body. Examples of cancer include but are not limited to, carcinoma, lymphoma, blastoma, sarcoma, and leukemia. More particular examples of such cancers include lung cancer, small-cell lung cancer, non-small cell lung (NSCL) cancer, bronchioloalviolar cell lung cancer, squamous cell cancer, adenocarcinoma of the lung, squamous carcinoma of the lung, cancer of the peritoneum, head and neck cancer, bone cancer, pancreatic cancer, skin cancer, cancer of the head or neck, cutaneous or intraocular melanoma, thyroid cancer, uterine cancer, gastrointestinal cancer, ovarian cancer, rectal cancer, cancer of the anal region, stomach cancer, gastric cancer, colon cancer, breast cancer, endometrial carcinoma, uterine cancer, carcinoma of the fallopian tubes, carcinoma of the cervix, carcinoma of the vagina, vulval cancer, Hodgkin's Disease, cancer of the esophagus, cancer of the small intestine, cancer of the endocrine system, cancer of the thyroid gland, cancer of the parathyroid gland, cancer of the adrenal gland, sarcoma of softtissue, cancer of the urethra, cancer of the penis, prostate cancer, cancer of the bladder, cancer of the kidney or ureter, renal cell carcinoma, carcinoma of the renal pelvis, mesothelioma, bladder cancer, liver cancer, hepatoma, hepatocellular cancer, cervical cancer, salivary gland carcinoma, biliay cancer, neoplasms of the central nervous system (CNS), spinal axis tumors, brain stem glioma, glioblastoma multiforme, astrocytomas, schwanomas, ependymonas, medulloblastomas, meningiomas, squamous cell carcinomas, pituitary adenoma and Ewings sarcoma, including refractory versions of any of the above cancers, or a combination of one or more of the above cancers. Antibodies and Antigen Binding Domains

[0079] Certain aspects of the present disclosure relate to antibodies, antibody fragments, and antigen binding domains that specifically bind human CD8b and / or human CD8ab. Any of the anti-CD8 antibodies of the present disclosure (e.g., that specifically bind human CD8b and / or human CD8ab) may find use in the fusion proteins, methods, and uses disclosed herein.

[0080] In some embodiments, the anti-CD8 antibody of the present disclosure specifically binds human CD8b and / or human CD8ab with at least 10-fold, at least 20-fold, at least 30-fold, at least 40-fold, at least 50-fold, at least 60-fold, at least 70-fold, at least 80-fold, at least 90-fold, at least 100-fold, or at least 200-fold higher affinity than its binding to human CD8a and / or human CD8aa, e.g., as expressed on natural killer (NK) cells (e.g., human NK cells). In some embodiments, the anti-CD8 antibody of the present disclosure specifically binds human CD8b and / or human CD8ab with at least 10-fold higher affinity than its binding to human CD8a and / or human CD8aa, e.g., as expressed on natural killer (NK) cells. In some embodiments, the human CD8b and / or human CD8ab are expressed on the surface of a human cell, e.g., a human T cell.

[0081] In some embodiments, the anti-CD8 antibody of the present disclosure specifically binds to a cell expressing a human CD8ab heterodimer on its surface (e.g., a human T cell) with an EC50 that is less than 1000nM. In some embodiments, the anti-CD8 antibody of the present disclosure specifically binds to human CD8+ T cells.

[0082] In some embodiments, the anti-CD8 antibody of the present disclosure is a human antibody or antibody fragment. In some embodiments, a human antibody or antibody fragment comprises human-derived CDRs and framework sequences in the variable domain, e.g., as isolated from a human or generated using a library with human antibody sequences (e.g., CDRsequences). In some embodiments, the anti-CD8 antibody of the present disclosure is a humanized antibody or antibody fragment. In some embodiments, a humanized antibody or antibody fragment comprises non-human-derived CDRs (e.g., from a mouse, rabbit, goat, etc.) and human-derived framework sequences in the variable domain. In some embodiments, a human or humanized antibody further comprises a human Fc region. In some embodiments, the human Fc region further comprises one or more Fc mutations, e.g., as disclosed herein. There are five major classes of intact antibodies: IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into subclasses (isotypes), e.g., IgGl, IgG2, IgG3, IgG4, IgA, and IgA2. The heavy chain constant domains that correspond to the different classes of antibodies are called Į, į, İ, Ȗ, and ^, respectively. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known.

[0083] Multiple definitions for the CDR sequences of antibody variable domains are known in the art. Unless otherwise specified, CDR sequences are described herein according to the definition of Kabat (see, e.g., Kabat et al., Sequences of Proteins of Immunological Interest, Fifth Edition, NIH Publication 91-3242, Bethesda MD (1991), vols.1-3). However, other definitions are known and contemplated for use. For example, in some embodiments, CDR sequences can be described by the definition of Chothia (see, e.g., Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987). Depending upon the specific CDR definition used, the precise framework sequences can also vary, but, as is known in the art, the first framework sequence (FW-1) refers to the sequence from the N-terminus of the VH or VL domain to the beginning of CDR-H1 / -L1, the second framework sequence (FW-2) refers to the sequence from end of CDR-H1 / -L1 to the beginning of CDR-H2 / -L2, the third framework sequence (FW-3) refers to the sequence from end of CDR- H2 / -L2 to the beginning of CDR-H3 / -L3, and the fourth framework sequence (FW-4) refers to the sequence from end of CDR-H3 / -L3 to the C-terminal boundary of the VH or VL domain.

[0084] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6. In some embodiments an anti CD8 antibody of the present disclosure comprises 1 2 or 3 heavy chainCDRs of antibody xhCD8v1 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v1 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:58 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:59.

[0085] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v8 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v8 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:185 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:186.

[0086] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:63. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v2 (e.g., as shown in Tables 1 3) and / or 1 2 or 3 light chain CDRs of antibody xhCD8v2 (eg as shown in Tables1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:62 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:63.

[0087] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v3 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v3 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:64 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:65.

[0088] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1 2 or 3 heavy chain CDRs of antibody xhCD8v4 (eg as shownin Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v4 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:66 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:67.

[0089] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v5 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v5 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:68 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:69.

[0090] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:71 In some embodiments an anti CD8 antibody of thepresent disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v6 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v6 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is human. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:70 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:71.

[0091] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v7 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v7 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is human. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:72 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:73.

[0092] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of X1X2AIS, wherein X1 is S, K, G, N, R, D, T, or G, and wherein X2 is Y, L, H, or F (SEQ ID NO:259), a CDR-H2 comprising the amino acid sequence of X1X2X3PX4X5X6X7X8X9YX10QKFX11G, wherein X1is G or H, X2is I or F, X3is I, N, or M, X4is G, N, H, S, R, I, or A, X5is A, N, H, S, T, F, or Y, X6is A, D, or G, X7is T, E, K, V, Q, or A, X8is A or T, X9is N or K, X10is A or N, and X11is Q or T (SEQ ID NO:260), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1 is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3 is A, L, P or Y X is I or L X is R A Q or S X is A or D and X is D E A or S (SEQ ID NO:261)and a VL domain comprising a CDR-L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1is R or G, X2is A or T, X3is Q or E, X4is E, N, T, S, A, K, D, G, R, or Q, X5 is Y or S, and X6 is A or V (SEQ ID NO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1 is A or S, X2 is T, S, E, Q, or D, X3 is N, R, A, E, or H, X4 is Q or A, and X5 is S or D (SEQ ID NO:263), and a CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1 is S, N, D, Q, A, or E, X2 is T, I, or S, X3is Y, L, or F, X4is D, G, T, E, Q, A, or Y, and X5is A, T, R, S, K, or Y (SEQ ID NO:264). In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequence RVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0093] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v9 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v9 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:245 and a VL domain comprising aCDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:246. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequence RVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0094] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:251; and the VL domain comprises the amino acid sequence of SEQ ID NO:252. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v12 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v12 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:251 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:252. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequenceRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0095] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v13 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v13 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:253 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:254. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequence RVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0096] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of X1YX2MS, wherein X1 is S, D, E, A, or Q and X2 is A, G, or T (SEQ ID NO:268), a CDR-H2 comprising the amino acid sequence of DIX1X2X3GX4X5TX6YADSVKG, wherein X1 is T, N, S, Q, E, H, R, or A, X2 is Y, W, F, or H, X3 is A, S, Q, E, or T, X4 is G or E, X5 is S or I, and X6 is A or G (SEQ ID NO:269), and a CDR-H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1is S or A, X2is N, H, A, D, L, Q, Y, or R, X3is A, N, S, or G, X4is A, V, R, E, or S, X5is D or S, X6is D, N, Q, E, S, T, or L, X7is L, F, or M, and X8is I, Y, or V (SEQ ID NO:270) and a VL domain comprising a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42). In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0097] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248. In some embodiments, an anti-CD8 antibody ofthe present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v10 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v10 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:247 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:248. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0098] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250. In some embodiments, the VH domain comprises the amino acid sequence of SEQ ID NO:249; and the VL domain comprises the amino acid sequence of SEQ ID NO:250. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v11 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v11 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:249 and a VL domain comprising a CDR-L1, CDR- L2, and CDR-L3 from the sequence of SEQ ID NO:250. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0099] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v14 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v14 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:255 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:256. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising thesequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0100] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257 and / or the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258. In some embodiments, an anti-CD8 antibody of the present disclosure comprises 1, 2, or 3 heavy chain CDRs of antibody xhCD8v15 (e.g., as shown in Tables 1-3) and / or 1, 2, or 3 light chain CDRs of antibody xhCD8v15 (e.g., as shown in Tables 1-3). In some embodiments, the antibody is humanized. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1, CDR-H2, and CDR-H3 from the sequence of SEQ ID NO:257 and a VL domain comprising a CDR-L1, CDR-L2, and CDR-L3 from the sequence of SEQ ID NO:258. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising thesequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0101] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33 and a VL domain comprising a CDR-L1 comprising the aminoacid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48. In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182.

[0102] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of GX1X2FX3X4X5, wherein X1 is G, Y, S, or A, X2 is T, S, G, R, N, or H, X3 is S, T, R, H, Y, G, or P, X4 is S, K, G, N, R, D, T, or G, and X5 is Y, L, H, or F (SEQ ID NO:265), a CDR-H2 comprising the amino acid sequence of X1PX2X3X4X5, wherein X1is I, N, or M, X2is G, N, H, S, R, I, or A, X3is A, N, H, S, T, F, or Y, X4is A, D, or G, and X5is T, E, K, V, Q, or A (SEQ ID NO:266), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3 is A, L, P, or Y, X4 is I or L, X5 is R, A, Q, or S, X6 is A or D, and X7 is D, E, A, or S (SEQ ID NO:267) and a VL domain comprising a CDR-L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1 is R or G, X2 is A or T, X3 is Q or E, X4 is E, N, T, S, A, K, D, G, R, or Q, X5 is Y or S, and X6 is A or V (SEQ IDNO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1is A or S, X2is T, S, E, Q, or D, X3is N, R, A, E, or H, X4is Q or A, and X5is S or D (SEQ ID NO:263), and a CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1 is S, N, D, Q, A, or E, X2 is T, I, or S, X3 is Y, L, or F, X4 is D, G, T, E, Q, A, or Y, and X5 is A, T, R, S, K, or Y (SEQ ID NO:264). In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS (SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0103] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS (SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0104] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:236. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS (SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0105] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS (SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and / or a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequenceGVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and / or a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

[0106] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of GFTFX1X2Y, wherein X1 is S, D, E, Q, S, or A and X2 is S, D, E, A, or Q (SEQ ID NO:271), a CDR-H2 comprising the amino acid sequence of X1X2X3GX4X5, wherein X1 is T, N, S, Q, E, H, R or A, X2 is Y, W, F, or H, X3 is A, S, Q, E, or T, X4 is G or E, and X5 is S or I (SEQ ID NO:272), and a CDR-H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1is S or A, X2is N, H, A, D, L, Q, Y, or R, X3is A, N, S, or G, X4is A, V, R, E, or S, X5is D or S, X6is D, N, Q, E, S, T, or L, X7is L, F, or M, and X8is I, Y, or V (SEQ ID NO:273) and a VL domain comprising a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42). In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAAS (SEQ ID NO:286), a FW-2 comprising the sequence AMSWVRQAPGKGLEWVSDI (SEQ ID NO:287), a FW-3 comprising the sequence TAYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:288), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0107] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAAS (SEQ ID NO:286) a FW 2 comprising the sequenceAMSWVRQAPGKGLEWVSDI (SEQ ID NO:287), a FW-3 comprising the sequence TAYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:288), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

[0108] In some embodiments, an anti-CD8 antibody of the present disclosure comprises a VH domain comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242 and a VL domain comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42. In some embodiments, the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAAS (SEQ ID NO:286), a FW-2 comprising the sequence AMSWVRQAPGKGLEWVSDI (SEQ ID NO:287), a FW-3 comprising the sequence TAYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:288), and / or a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285). In some embodiments, the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and / or a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296). In some embodiments, the present disclosure provides an anti-CD8 antibody comprising a VH domain comprising CDR-H1, CDR-H2, and CDR-H3 sequences of a single antibody listed in Table 1 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of the single antibody listed in Table 1. For example, the anti- CD8 antibody comprises the six CDRs of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, xhCD8v15, V9 family, or V11 family shown in Table 1. In some embodiments, the present disclosure provides an anti-CD8 antibody comprising a VHdomain comprising CDR-H1, CDR-H2, and CDR-H3 sequences of a single antibody listed in Table 2 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of the single antibody listed in Table 2. For example, the anti-CD8 antibody comprises the six CDRs of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, xhCD8v15, V9 family, or V11 family shown in Table 2. In some embodiments, the present disclosure provides a fusion protein comprising an anti-CD8 antibody comprising a VH domain comprising CDR-H1, CDR-H2, and CDR-H3 sequences of the single antibody listed in Table 1 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of a single antibody listed in Table 1. For example, the anti-CD8 antibody of the fusion protein comprises the six CDRs of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, xhCD8v15, V9 family, or V11 family shown in Table 1. In some embodiments, the present disclosure provides a fusion protein comprising an anti-CD8 antibody comprising a VH domain comprising CDR-H1, CDR-H2, and CDR-H3 sequences of a single antibody listed in Table 2 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of the single antibody listed in Table 2. For example, the anti-CD8 antibody of the fusion protein comprises the six CDRs of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, xhCD8v15, V9 family, or V11 family shown in Table 2. In some embodiments, the present disclosure provides an anti-CD8 antibody comprising a VH domain comprising CDR-H1, CDR- H2, and CDR-H3 sequences of a VH domain listed in Table 3 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of a VL domain listed in Table 3 (in some embodiments, the VH and VL domains are from the same single antibody listed in Table 3). For example, the anti-CD8 antibody comprises the VH and VL of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, or xhCD8v15 shown in Table 3. In some embodiments, the present disclosure provides a fusion protein comprising an anti-CD8 antibody comprising a VH domain comprising CDR-H1, CDR-H2, and CDR-H3 sequences of a VH domain listed in Table 3 and a VL domain comprising CDR-L1, CDR-L2, and CDR-L3 sequences of a VL domain listed in Table 3 (in some embodiments, the VH and VL domains arefrom the same single antibody listed in Table 3). In some embodiments, the present disclosure provides an anti-CD8 antibody comprising a VH domain sequence and a VL domain sequence for a single antibody as listed in Table 3. In some embodiments, the present disclosure provides a fusion protein comprising an anti-CD8 antibody comprising a VH domain sequence and a VL domain sequence for a single antibody as listed in Table 3. For example, the anti-CD8 antibody of the fusion protein comprises the VH and VL of antibody xhCD8v1, xhCD8v1.1, xhCD8v2, xhCD8v3, xhCD8v4, xhCD8v5, xhCD8v6, xhCD8v7, xhCD8v8, xhCD8v9, xhCD8v10, xhCD8v11, xhCD8v12, xhCD8v13, xhCD8v14, or xhCD8v15 shown in Table 3. Table 1. Anti-CD8 antibody CDRs (Kabat)Table 2. Anti-CD8 antibody CDRs (Chothia)Table 3. Anti-CD8 antibody variable domain sequencesFusion proteins

[0109] Further provided herein are fusion proteins comprising any one of the anti-CD8 antibodies, or antigen binding domains, or antibody fragments disclosed herein. In some embodiments, a fusion protein of the present disclosure comprises a first moiety comprising a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab (e.g., any one of the anti-CD8 antibodies described supra) and a second moiety comprising a cytokine, chemokine, or growth factor. In some embodiments, the first moiety is fused to the second moiety directly. In some embodiments, the first moiety is fused to the second moiety via a linker. Exemplary and non-limiting illustrations of fusion proteins of the present disclosure are depicted in FIG.7. Fusion protein formats

[0110] In some embodiments, the first moiety comprises an antibody (e.g., an anti-CD8 antibody of the present disclosure). In some embodiments, the first moiety comprises an antibody fragment (e.g., an anti-CD8 antibody fragment of the present disclosure). In some embodiments, the first moiety comprises a single chain antibody or single chain variable fragment (scFv). In some embodiments, the first moiety comprises a VHH antibody. In some embodiments, the first moiety comprises one or two antibody heavy chain polypeptides and one or two antibody light chain polypeptides (e.g., of an anti-CD8 antibody of the present disclosure). In some embodiments, the first moiety comprises the 3 heavy chain CDRs and / or 3 light chain CDRs of a single anti-CD8 antibody of the present disclosure, e.g., as shown in Tables 1-3. In some embodiments, the first moiety comprises the VH and / or VL domain(s) of a single anti-CD8 antibody of the present disclosure, e.g., as shown in Table 3. In some embodiments, the first moiety further comprises one or two human IgG Fc domains. In some embodiments, the one or two human IgG Fc domains are IgG1, IgG2, IgG3 or IgG4 Fc domains. In some embodiments, the one or two human IgG Fc domains do not have the C-terminus lysine residue. In some embodiments, the one or two human IgG Fc domains comprise amino acid modifications (such as substitutions, deletions, additions, etc.). In some embodiments, the Fc domain modifications promote heterodimeric formation (e.g., as shown in Table 4). In some embodiments, the one or two Fc domains comprise Fc gamma-null mutations.

[0111] In some embodiments, the first moiety comprises two antibody heavy chain polypeptides comprising a structure according to formula [I] from N terminus to C terminus:VH-CH1-hinge-CH2-CH3 [I] and two antibody light chain polypeptides comprising a structure according to formula [II], from N-terminus to C-terminus: VL-CL [II] wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain. In some embodiments, the N-terminus of the second moiety is fused to the C-terminus of one of the two CH3 domains (see, e.g., format A in FIG.7).

[0112] In some embodiments, the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N-terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain. In some embodiments, the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the second antibody heavy chain polypeptide (see, e.g., format B in FIG.7). In some embodiments, the N- terminus of the second moiety is fused to the C-terminus of the CH3 domain of the first antibody heavy chain polypeptide (see, e.g., format D in FIG. 7).

[0113] In some embodiments, the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N-terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I],an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain. In some embodiments, the C-terminus of the second moiety is fused to the N-terminus of the hinge domain of the second antibody heavy chain polypeptide (see, e.g., format C in FIG.7).

[0114] In some embodiments, an anti-CD8 antibody of the present disclosure is a multispecific (e.g., bispecific) antibody or antibody fragment. For example, in some embodiments, the multispecific antibody (e.g., bispecific antibody) comprises a first antigen binding domain that binds to CD8 (e.g., as described supra) and a second antigen binding domain that binds a target of interest. In some embodiments, a bispecific antibody can be generated via fusion of an additional binding site to either the heavy or light chain of an immunoglobulin. Examples of the additional binding site include but not limited to variable regions, scFv, Fab, VHH, and peptide.

[0115] In some embodiments, In some embodiments, the recombinant bispecific antibodies disclosed herein can be very roughly classified in two categories, namely i) formats resulting from the combination of variable regions only and ii) formats combining variable regions with Fc domains. Representatives of the first category are tandem scFv (taFv), diabodies (Db), DART, single-chain diabodies (scDbs), Fab-Fc, tandem Fab, Dual variable region Fab and tandem dAb / VHH. The two variable regions can be linked together via covalent bonds or non- covalent interaction.

[0116] Noncovalent interaction may involve the use of heterodimerization modules such as leucine zipper, dock-and-lock methods of using regulatory subunit of cAMP-dependent protein kinase (PKA) and the anchoring domains of A kinase anchor proteins (AKAPs) or knob-into-holes CH3 domain (U.S. Pat. No.5,731,168; U.S. Pat. No.7,695,936; Ridgway et al., Prot Eng 9, 617-621 (1996) and Carter, J Immunol Meth 248, 7-15 (2001)) to pair up the variable regions.

[0117] In some embodiments, bispecific antibodies are generated on the natural immunoglobulin architecture containing two pairs of heavy chain and light chain combination with each pair having distinct binding specificity. Homodimerization of the two heavy chains in an IgG is mediated by the CH3 interaction. To promote heterodimeric formation, genetic modifications are introduced to the two respective CH3 regions. There heterodimerization mutations often involve steric repulsion, charge steering interaction, or interchain disulfide bond formation. Exemplary and non-limiting Fc modifications to promote heterodimerization include the following: Table 4. Exemplary Fc modifications to promote heterodimerization.

[0118] In some embodiments, bispecific antibody can be generated by post-production assembly from half-antibodies, thereby solving the issues of heavy and light chain mispairing. These antibodies often contain modification to favor heterodimerization of half-antibodies. Exemplary systems include but not limited to the knob-into-hole, IgG1 (EEE - RRR), IgG2 (EEE - RRRR) (Strop et al. J Mol Biol (2012)) and DuoBody (F405L-K409R), listed in Table 5. In such case, half-antibody is individually produced in separate cell line and purified. The purified antibodies were then subjected to mild reduction to obtain half-antibodies, which were then assembled into bispecific antibodies. Heterodimeric bispecific antibody was then purified from the mixture using conventional purifications methods.

[0119] In some embodiments, strategies on bispecific antibody generation that do not rely on the preferential chain pairing can also be employed. These strategies typically involve introducing genetic modification on the antibody in such a manner that the heterodimer will have distinct biochemical or biophysical properties from the homodimers; thus the post-assembled or expressed heterodimer can be selectively purified from the homodimers. One example was to introduce H435R / Y436F in IgG1 CH3 domain to abolish the Fc binding to protein A resin and then co-express the H435R / Y436F variant with a wildtype Fc. The resulting homodimeric antibodies containing two copies of H435R / Y436F cannot bind to the Protein A column, while heterodimeric antibody comprising one copy of H435R / Y436F mutation will have a decreased affinity for protein A as compared to the strong interaction from homodimeric wildtype antibody (Tustian et al Mabs 2016). Other examples include kappa / lambda antibody (Fischer et al., Nature Communication 2015) and introduction of differential charges (E357Q, S267K or N208D / Q295E / N384D / Q418E / N421D) on the respective chains (US 2018 / 0142040 A1; (Strop et al. J Mol Biol (2012)).

[0120] In some embodiments, bispecific antibody can be generated via fusion of an additional binding site to either the heavy or light chain of an immunoglobulin. Examples of the additional binding site include but not limited to variable regions, scFv, Fab, VHH, and peptide.Fusion protein Fc regions

[0121] In some embodiments, an antibody or fusion protein of the present disclosure comprises an Fc region. In some embodiments, the Fc region comprises one or more mutations that reduce or eliminate FcȖR binding and / or effector function. In some embodiments, the Fc region (e.g., an IgG1 Fc region) comprises a substitution at one or more of the following positions: C220, C226, C229, E233, L234, L235, G237, P238, S239 D265, S267, N297, L328, P331, K322, A327 and P329. In some embodiments, the Fc region (e.g., an IgG2 Fc region) comprises a substitution at one or more of the following positions: V234, G237, D265, H268, N297, V309, A330, A331, K322. In some embodiments, the Fc region (e.g., an IgG4 Fc region) comprises a substitution at one or more of the following positions: L235, G237, D265 and E318. In some embodiments, the Fc region (e.g., an IgG1 Fc region) comprises one or more of the following mutations or groups of mutations: N297A, N297Q, N297G, D265A / N297A, D265A / N297Q, C220S / C226S / C229S / P238S, S267E / L328F, C226S / C229S / E233P / L234V / L235A, L234F / L235E / P331S, L234A / L235A, L234A / L235A / G237A, L234A / L235A / G237A / K322A, L234A / L235A / G237A / A330S / A331S, L234A / L235A / P329G,E233P / L234V / L235A / G236del / S239K, E233P / L234V / L235A / G236del / S267K, E233P / L234V / L235A / G236del / S239K / A327G, E233P / L234V / L235A / G236del / S267K / A327G and E233P / L234V / L235A / G236del, L234A / L235A / G237deleted. In some embodiments, the Fc region (e.g., an IgG2 Fc region) comprises one or more of the following mutations or groups of mutations: A330S / A331S, V234A / G237A, V234A / G237A / D265A, D265A / A330S / A331S, V234A / G237A / D265A / A330S / A331S, and H268Q / V309L / A330S / A331S. In some embodiments, the Fc region (e.g., an IgG4 Fc region) comprises one or more of the following mutations or groups of mutations: L235A / G237A / E318A, D265A, L235A / G237A / D265A and L235A / G237A / D265A / E318A. In some embodiments, the Fc region comprises one, two, three, or all of the following mutations: L234A, L235A, G237A, and K322A, numbering according to EU index. In some embodiments, the Fc region comprises one, two, or all of the following mutations: L234A, L235A, and G237A, numbering according to EU index.

[0122] In some embodiments, said first and second Fc domains of the fusion protein contain one or more of the following Fc mutations to decrease effector function according to EU numbering: L234A, L235A, G237A, and K322A. In some embodiments, said first and second Fcdomains of the fusion protein contain the following Fc mutations to decrease effector function according to EU numbering: L234A, L235A, and G237A. In some embodiments, said first and second Fc domains of the fusion protein contain the following Fc mutations to decrease effector function according to EU numbering: L234A, L235A, G237A, and K322A. In some embodiments, said first and second Fc domains of the fusion protein contain the following amino acid substitutions to facilitate heterodimeric formation: Y349C / T366W (knob) and S354C, T366S, L368A and Y407V (hole).

[0123] In some embodiments, the heterodimeric mutations and / or mutations to modify Fc gamma receptor binding resulted in reduction of Fc stability. Therefore, additional mutation(s) was added to the Fc region to increase its stability. For example, one or more pairs of disulfide bonds such as A287C and L306C, V259C and L306C, R292C and V302C, and V323C and I332C are introduced into the Fc region. Another example is to introduce S228P to IgG4 based bispecific antibodies to stabilize the hinge disulfide. Additional example includes introducing K338I, A339K, and K340S mutations to enhance Fc stability and aggregation resistance (Gao et al, 2019 Mol Pharm. 2019;16:3647). Fusion protein cytokines

[0124] In some embodiments, the second moiety induces activation of CD8+ T cells. In some embodiments, the second moiety comprises a polypeptide that induces signaling via IL2REJ^^^For example, in some embodiments, the second moiety comprises an IL-15 polypeptide (e.g., a human IL-15 polypeptide or derivative thereof) or a neoleukin. In some embodiments, the second moiety comprises an IL-21 polypeptide (e.g., a human IL-21 polypeptide or derivative thereof).

[0125] In some embodiments, the second moiety comprises an IL-2 polypeptide (e.g., a human IL-2 polypeptide or derivative thereof).

[0126] In some embodiments, the mutant IL-2 polypeptide has a binding affinity to IL-2RĮ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2RĮ. In some embodiments, the mutant IL-2 polypeptide has a binding affinity to IL-2Rȕ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL- 2Rȕ. In some embodiments, the mutant IL-2 polypeptide has a binding affinity to IL-2RȖ that isreduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2RȖ. Differences in binding affinity of wild-type and disclosed mutant polypeptide for IL-2RD and IL-2RE can be measured, e.g., in standard surface plasmon resonance (SPR) assays that measure affinity of protein-protein interactions familiar to those skilled in the art. Differences in binding affinity of wild-type and disclosed mutant polypeptide for IL-2RJ cannot reliably be measured by SPR assays as the affinity of wild-type IL-2 polypeptide for IL-2RJ^is very low. Instead, their reduced affinity to IL-2RJ can be deduced by performing an in vitro assay that measures pSTAT5 and compares the activity of IL-2 polypeptides with and without the IL-2RJ affinity-reducing substitution on IL-2R- expressing cells. Exemplary sequences for IL-2RĮ, IL-2Rȕ, and IL-2RȖ are provided below. IL-2RĮ:

[0127] In some embodiments, the IL-2 polypeptide is a mutant IL-2 polypeptide comprising one or more mutations relative to a human IL-2 polypeptide comprising the sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTFKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:81). In some embodiments, the mutant IL-2 polypeptides of the present disclosure have one or more, two or more, or three or more affinity-reducing amino acid substitutions relative to the wild-type mature IL-2 polypeptide, e.g., having the amino acid sequence of SEQ ID NO:81. In some embodiments, one or more, two or more, or three or more substituted residues, are selected from the following group: Q11, H16, L18, L19, D20, D84, S87, Q22, R38, F42, K43, Y45, E62, P65, E68, V69, L72, D84,^S87, N88, V91, I92, T123, Q126, S127, I129, and S130. Decreased affinity to IL-2RD^may be obtained by substituting one or more of the following residues in the sequence of the wild-type mature IL-2 polypeptide: R38, F42, K43, Y45, E62, P65, E68, V69, and L72. Decreased affinity to IL-2RE^may be obtained by substituting one or more of the following residues: E15, H16, L19, D20, D84, S87, N88, V91, and I92. Decreased affinity to IL-2RJ^may be obtained by substituting one or more of the following residues in the sequence of the wild-type mature IL-2 polypeptide: Q11, L18, Q22, T123, Q126, S127, I129, and S130.

[0128] In some embodiments, the mutant IL-2 polypeptide comprises an F42A or F42K amino acid substitution relative to the wild-type mature IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises an F42A or F42K amino acid substitution and an R38A, R38D, R38E, E62Q, E68A, E68Q, E68K, or E68R amino acid substitution relative to the wild-type mature IL-2 amino acid sequence. For example, in some embodiments, the mutant IL-2 polypeptide comprises F42A; R38A and F42A; R38D and F42A; R38E and F42A; F42A and E62Q; F42A and E68A; F42A and E68Q; F42A and E68K; F42A and E68R; or R38A and F42K amino acid substitution(s) relative to the wild-type mature IL-2 amino acid sequence, e.g., as shown in SEQ ID NO:81. In some embodiments, the mutant IL-2 polypeptide comprises R38E and F42A amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38D and F42A amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises F42A and E62Q amino acid substitutions relative to the wild- type IL 2 amino acid sequence In some embodiments the mutant IL 2 polypeptide comprisesR38A and F42K amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38D and F42A amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38A and F42K amino acid substitutions relative to the wild- type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises F42A and E62Q amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises an H16E, H16D, D20N, M23A, M23R, M23K, D84L, D84N, D84V, D84H, D84Y, D84R, D84K, S87K, S87A, N88A, N88D, N88G, N88S, N88T, N88R, N88I, V91A, V91T, V91E, I92A, E95S, E95A, E95R, T123A, T123E, T123K, T123Q, Q126A, Q126S, Q126T, Q126E, S127A, S127E, S127K, or S127Q amino acid substitution relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises F42A; R38A and F42A; R38D and F42A; R38E and F42A; F42A and E62Q; F42A and E68A; F42A and E68Q; F42A and E68K; F42A and E68R; or R38A and F42K amino acid substitution(s) relative to the wild-type mature IL-2 amino acid sequence and an H16E, H16D, D20N, M23A, M23R, M23K, D84L, D84N, D84V, D84H, D84Y, D84R, D84K, S87K, S87A, N88A, N88D, N88G, N88S, N88T, N88R, N88I, V91A, V91T, V91E, I92A, E95S, E95A, E95R, T123A, T123E, T123K, T123Q, Q126A, Q126S, Q126T, Q126E, S127A, S127E, S127K, or S127Q amino acid substitution relative to the wild-type mature IL-2 amino acid sequence, e.g., as shown in SEQ ID NO:81. For example, in some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and H16E amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and H16D amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and D84K amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and D84R amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88S amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88A amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88G amino acid substitutions relative to the wild-type IL-2 aminoacid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88R amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88T amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and N88D amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and V91E amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises R38E, F42A, and Q126S amino acid substitutions relative to the wild-type IL-2 amino acid sequence. In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E and F42A; R38D and F42A; F42A and E62Q; R38A and F42K; R38E, F42A, and N88S; R38E, F42A, and N88A; R38E, F42A, and N88G; R38E, F42A, and N88R; R38E, F42A, and N88T; R38E, F42A, and N88D; R38E, F42A, and V91E; R38E, F42A, and D84H; R38E, F42A, and D84K; R38E, F42A, and D84R; H16D, R38E and F42A; H16E, R38E and F42A; R38E, F42A and Q126S; R38D, F42A and N88S; R38D, F42A and N88A; R38D, F42A and N88G; R38D, F42A and N88R; R38D, F42A and N88T; R38D, F42A and N88D; R38D, F42A and V91E; R38D, F42A, and D84H; R38D, F42A, and D84K; R38D, F42A, and D84R; H16D, R38D and F42A; H16E, R38D and F42A; R38D, F42A and Q126S; R38A, F42K, and N88S; R38A, F42K, and N88A; R38A, F42K, and N88G; R38A, F42K, and N88R; R38A, F42K, and N88T; R38A, F42K, and N88D; R38A, F42K, and V91E; R38A, F42K, and D84H; R38A, F42K, and D84K; R38A, F42K, and D84R; H16D, R38A, and F42K; H16E, R38A, and F42K; R38A, F42K, and Q126S; F42A, E62Q, and N88S; F42A, E62Q, and N88A; F42A, E62Q, and N88G; F42A, E62Q, and N88R; F42A, E62Q, and N88T; F42A, E62Q, and N88D; F42A, E62Q, and V91E; F42A, E62Q, and D84H; F42A, E62Q, and D84K; F42A, E62Q, and D84R; H16D, F42A, and E62Q; H16E, F42A, and E62Q; F42A, E62Q, and Q126S; R38E, F42A, and C125A; R38D, F42A , and C125A; F42A, E62Q, and C125A; R38A, F42K, and C125A; R38E, F42A, N88S, and C125A; R38E, F42A, N88A, and C125A; R38E, F42A, N88G, and C125A; R38E, F42A, N88R, and C125A; R38E, F42A, N88T, and C125A; R38E, F42A, N88D, and C125A; R38E, F42A, V91E, and C125A; R38E, F42A, D84H, and C125A; R38E, F42A, D84K, and C125A; R38E, F42A, D84R, and C125A; H16D, R38E, F42A, and C125A;H16E, R38E, F42A, and C125A; R38E, F42A, C125A and Q126S; R38D, F42A, N88S, and C125A; R38D, F42A, N88A, and C125A; R38D, F42A, N88G, and C125A; R38D, F42A, N88R, and C125A; R38D, F42A, N88T, and C125A; R38D, F42A, N88D, and C125A; R38D, F42A, V91E, and C125A; R38D, F42A, D84H, and C125A; R38D, F42A, D84K, and C125A; R38D, F42A, D84R, and C125A; H16D, R38D, F42A, and C125A; H16E, R38D, F42A, and C125A; R38D, F42A , C125A, and Q126S; R38A, F42K, N88S, and C125A; R38A, F42K, N88A, and C125A; R38A, F42K, N88G, and C125A; R38A, F42K, N88R, and C125A; R38A, F42K, N88T, and C125A; R38A, F42K, N88D, and C125A; R38A, F42K, V91E, and C125A; R38A, F42K, D84H, and C125A; R38A, F42K, D84K, and C125A; R38A, F42K, D84R, and C125A; H16D, R38A, F42K, and C125A; H16E, R38A, F42K, and C125A; R38A, F42K, C125A and Q126S; F42A, E62Q, N88S, and C125A; F42A, E62Q, N88A, and C125A; F42A, E62Q, N88G,and C125A; F42A, E62Q, N88R,and C125A; F42A, E62Q, N88T,and C125A; F42A, E62Q, N88D,and C125A; F42A, E62Q, V91E, and C125A; F42A, E62Q, and D84H, and C125A; F42A, E62Q, and D84K, and C125A; F42A, E62Q, and D84R, and C125A; H16D, F42A, and E62Q, and C125A; H16E, F42A, E62Q, and C125A; F42A, E62Q, C125A and Q126S; F42A, N88S, and C125A; F42A, N88A, and C125A; F42A, N88G, and C125A; F42A, N88R, and C125A; F42A, N88T, and C125A; F42A, N88D, and C125A; F42A, V91E, and C125A; F42A, D84H, and C125A; F42A, D84K, and C125A; F42A, D84R, and C125A; H16D, F42A, and C125A; H16E, F42A, and C125A; and F42A, C125A and Q126S. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one, two, three, four, or five amino acid substitutions relative to SEQ ID NO:81, and wherein the one, two, three, four, or five substitution(s) comprise substitution(s) at positions of SEQ ID NO:81 selected from the group consisting of: Q11, H16, L18, L19, D20, Q22, R38, F42, K43, Y45, E62, P65, E68, V69, L72, D84, S87, N88, V91, I92, T123, Q126, S127, I129, and S130. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E and F42A; R38D and F42A; F42A and E62Q; R38A and F42K; R38E, F42A, and N88S; R38E, F42A, and N88A; R38E, F42A, and N88G; R38E, F42A, and N88R; R38E, F42A, and N88T; R38E, F42A, and N88D; R38E, F42A, and V91E; R38E, F42A, and D84H; R38E, F42A, and D84K; R38E, F42A, and D84R; H16D, R38E and F42A; H16E, R38E and F42A; R38E, F42A and Q126S; R38D, F42A and N88S; R38D, F42A and N88A; R38D, F42A and N88G; R38D,F42A and N88R; R38D, F42A and N88T; R38D, F42A and N88D; R38D, F42A and V91E; R38D, F42A, and D84H; R38D, F42A, and D84K; R38D, F42A, and D84R; H16D, R38D and F42A; H16E, R38D and F42A; R38D, F42A and Q126S; R38A, F42K, and N88S; R38A, F42K, and N88A; R38A, F42K, and N88G; R38A, F42K, and N88R; R38A, F42K, and N88T; R38A, F42K, and N88D; R38A, F42K, and V91E; R38A, F42K, and D84H; R38A, F42K, and D84K; R38A, F42K, and D84R; H16D, R38A, and F42K; H16E, R38A, and F42K; R38A, F42K, and Q126S; F42A, E62Q, and N88S; F42A, E62Q, and N88A; F42A, E62Q, and N88G; F42A, E62Q, and N88R; F42A, E62Q, and N88T; F42A, E62Q, and N88D; F42A, E62Q, and V91E; F42A, E62Q, and D84H; F42A, E62Q, and D84K; and F42A, E62Q, and D84R.

[0129] In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with a further amino acid substitution relative to SEQ ID NO:81 at position C125. In some embodiments, the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E, F42A, and C125A; R38D, F42A , and C125A; F42A, E62Q, and C125A; R38A, F42K, and C125A; R38E, F42A, N88S, and C125A; R38E, F42A, N88A, and C125A; R38E, F42A, N88G, and C125A; R38E, F42A, N88R, and C125A; R38E, F42A, N88D, and C125A; R38E, F42A, N88T, and C125A; R38E, F42A, V91E, and C125A; R38E, F42A, D84H, and C125A; R38E, F42A, D84K, and C125A; R38E, F42A, D84R, and C125A; H16D, R38E, F42A, and C125A; H16E, R38E, F42A, and C125A; R38E, F42A, C125A and Q126S; R38D, F42A, N88S, and C125A; R38D, F42A, N88A, and C125A; R38D, F42A, N88G, and C125A; R38D, F42A, N88R, and C125A; R38D, F42A, N88T, and C125A; R38D, F42A, N88D, and C125A; R38D, F42A, V91E, and C125A; R38D, F42A, D84H, and C125A; R38D, F42A, D84K, and C125A; R38D, F42A, D84R, and C125A; H16D, R38D, F42A, and C125A; H16E, R38D, F42A, and C125A; R38D, F42A , C125A, and Q126S; R38A, F42K, N88S, and C125A; R38A, F42K, N88G, and C125A; R38A, F42K, N88R, and C125A; R38A, F42K, N88T, and C125A; R38A, F42K, N88D, and C125A; R38A, F42K, N88A, and C125A; R38A, F42K, V91E, and C125A; R38A, F42K, D84H, and C125A; R38A, F42K, D84K, and C125A; R38A, F42K, D84R, and C125A; H16D, R38A, F42K, and C125A; H16E, R38A, F42K, and C125A; R38A, F42K, C125A and Q126S; F42A, E62Q, N88S, and C125A; F42A, E62Q, N88A, and C125A; F42A, E62Q, N88G, and C125A; F42A, E62Q, N88R, and C125A; F42A, E62Q, N88T, and C125A; F42A, E62Q, N88D, and C125A; F42A, E62Q, V91E, and C125A; F42A, E62Q, and D84H, andC125A; F42A, E62Q, and D84K, and C125A; F42A, E62Q, and D84R, and C125A; H16D, F42A, and E62Q, and C125A; H16E, F42A, E62Q, and C125A; F42A, E62Q, C125A and Q126S; F42A, N88S, and C125A; F42A, N88A, and C125A; F42A, N88G, and C125A; F42A, N88R, and C125A; F42A, N88T, and C125A; F42A, N88D, and C125A;F42A, V91E, and C125A; F42A, D84H, and C125A; F42A, D84K, and C125A; F42A, D84R, and C125A; H16D, F42A, and C125A; H16E, F42A, and C125A; and F42A, C125A and Q126S.

[0130] In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence ofWITFCQSIISTLT (SEQ ID NO:97). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTDMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINEIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:98). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTDMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRHLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:99). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEDLLLDLQMILNGINNYKNPKLTDMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:100). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEELLLDLQMILNGINNYKNPKLTDMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:101). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTDMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCSSIISTLT (SEQ ID NO:102). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISSINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:103). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISAINVIVLELKGSETTFMCEYADETATIVEFLNR WITFCQSIISTLT (SEQ ID NO:104). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCLcomprises the amino acid sequence ofi h i id fEEELKPLEEVLNLAQSKNFHLRPRDLISAINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:136). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINEIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:137). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRHLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:138). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEDLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:139). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEELLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:140). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFASSIISTLT (SEQ ID NO:141). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEQLKPLEEVLNLAQSKNFHLRPRDLISSINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:142). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEQLKPLEEVLNLAQSKNFHLRPRDLISAINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:143). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence ofcomprises the amino acid sequence ofcomprises the amino acid sequence ofAPTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRKLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:209). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTAMLTKKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRRLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:210). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEQLKPLEEVLNLAQSKNFHLRPRDLISGINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:211). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEQLKPLEEVLNLAQSKNFHLRPRKLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:212). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEQLKPLEEVLNLAQSKNFHLRPRRLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:213). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRDLISGINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:214). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRKLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:215). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of APTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTAKFYMPKKATELKHLQCL EEELKPLEEVLNLAQSKNFHLRPRRLISNINVIVLELKGSETTFMCEYADETATIVEFLNR WITFAQSIISTLT (SEQ ID NO:216). In some embodiments, the mutant IL-2 polypeptideWITFCQSIISTLT (SEQ ID NO:360). In some embodiments, the mutant IL-2 polypeptidecomprises the amino acid sequence ofWITFAQSIISTLT (SEQ ID NO:383). In some embodiments, the mutant IL-2 polypeptide comprises the amino acid sequence of an IL-2 polypeptide listed in Table 7. Table 7. Exemplary IL-2 polypeptide sequences

[0131] In some embodiments, the mutant IL-2 polypeptides of the present disclosure also contain other modifications, including but not limited to mutations and deletions, that provide additional advantages such as improved biophysical properties. Improved biophysical properties include but are not limited to improved thermostability, aggregation propensity, acid reversibility, viscosity, and production in a mammalian or bacterial or yeast cell. For example, residue C125 may be replaced with a neutral amino acid such as serine, alanine, threonine or valine; and N terminal A1 residue could be deleted, both of which were described in U.S. Pat. No.4,518,584. Mutant IL-2 polypeptides may also include a mutation of the residue M104, such as M104A, as described in U.S. Pat. No.5,206,344. Thus, in certain embodiments the mutant IL- 2 polypeptide of the present disclosure comprises the amino acid substitution C125A. In other embodiments, one, two, or three N-terminal residues are deleted. Fusion protein linkers

[0132] In some embodiments, a fusion protein of the present disclosure comprises a linker. In some embodiments, the linker is a chemical linker (for example, see disclosed in Protein Engineering, 9(3), 299-305, 1996). Synthetic chemical linkers include crosslinking agents that are routinely used to crosslink peptides, for example, N-hydroxy succinimide (NHS), disuccinimidyl suberate (DSS), bis(succinimidyl) suberate (BS3), dithiobis(succinimidyl propionate) (DSP), dithiobis(succinimidyl propionate) (DTSSP), ethylene glycol bis(succinimidyl succinate) (EGS), ethylene glycol bis(sulfosuccinimidyl succinate) (sulfo- EGS), disuccinimidyl tartrate (DST), disulfosuccinimidyl tartrate (sulfo-DST), bis[2- (succinimidoxycarbonyloxy)ethyl] sulfone (BSOCOES), and bis[2- (succinimidoxycarbonyloxy)ethyl] sulfone (sulfo-BSOCOES).

[0133] In some embodiments, the linker is an amino acid- or peptide-based linker. In some embodiments, the polypeptide linker is a peptide with a length of at least 5 amino acids, preferably with a length of 5 to 100, more preferably of 10 to 50 amino acids. In one embodiment, said peptide linker is G, S, GS, SG, SGG, GGS, and GSG (with G=glycine and S=serine). In some embodiments, the linker comprises the sequence (GGGS)xGn (SEQ ID NO:74), (GGGGS)xGn (SEQ ID NO:75), (GGGGGS)xGn (SEQ ID NO:76), S(GGGS)xGn (SEQ ID NO:386), S(GGGGS)xGn (SEQ ID NO:387), or S(GGGGGS)xGn (SEQ ID NO:388), wherein x=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and wherein n=0, 1, 2 or 3. In someembodiments, the linker comprises the sequence GGGGSGGGGSGGGGS (SEQ ID NO:79) or SGGGGSGGGGSGGGGS (SEQ ID NO:389). Fusion protein properties

[0134] In some embodiments, the fusion protein induces activation of cells expressing a human CD8ab heterodimer with at least 2-fold, at least 5-fold, or at least 10-fold higher potency than activation of cells expressing a human CD8aa homodimer. In some embodiments, the fusion protein induces activation of CD8+ T cells with at least 2-fold, at least 5-fold, or at least 10-fold higher potency than activation of NK cells. In some embodiments, potency of activation is measured by EC50, as assessed by cell proliferation. Exemplary assays are further described infra.

[0135] Preferential activity of the targeted IL-2 fusion proteins comprising the mutant IL-2 polypeptides on antigen-expressing cells is demonstrated in assays that contain antigen- expressing and antigen-non expressing cells that also express IL-2REJ or IL-2RDEJ. One such assay is an in vitro assay that measures STAT5 (pSTAT5) phosphorylation and / or expression of the proliferation marker Ki-67 in human immune cells, such as human peripheral blood and / or tumor-infiltrating immune cells upon exposure to IL-2 polypeptides. In one format of the assay, the activity of the targeted IL-2 fusion protein is measured on antigen-expressing and non- expressing cells to demonstrate the selectivity on antigen-expressing cells. In another format of the assay, the activity of the targeted IL-2 fusion protein comprising the mutant IL-2 polypeptide on antigen-expressing cells is compared to that of the untargeted IL-2 fusion protein comprising the same mutant IL-2 polypeptide and a control antibody not recognizing any antigens on antigen-expressing cells to demonstrate the magnitude of rescue in signaling of the mutant IL-2 polypeptide when fused to an antigen binding molecule.

[0136] In some embodiments, the fusion protein of the present^disclosure containing CD8b antigen binding molecules activates CD8b+ IL-2RE+ cells over CD8b- IL-2RE+ cells by at least 10-fold, at least 50-fold, or at least 100-fold. In some embodiments, said fusion protein activates CD8b+ IL-2RE+ cells more than 50-fold, 100 fold, or 200 fold compared to a fusion molecule comprising the said IL-2 mutant polypeptide and a control antibody not binding to any antigens expressed on said cells. Said cell activation by the IL-2 fusion protein is determined bymeasuring the expression of pSTAT5 or the cell proliferation marker Ki67 in said cells following the treatment with said IL-2 fusion protein.

[0137] In some embodiments, a fusion protein of the present disclosure displays one or more of the following: binds human CD8 and does not block an interaction of CD8 with MHC class I; and activates CD8+ T cells with at least 10-fold, 25-fold, 50-fold, 100-fold, 250-fold, 500-fold, or 1000-fold greater potency, e.g., as compared to activation of NK cells. In some embodiments, whether an anti-CD8 antibody or fusion protein of the present disclosure blocks the interaction of CD8 with MHC class I can be assayed, e.g., by assaying activation status of CD8+ T cells (e.g., upon antigen stimulation) in the presence or absence of the anti-CD8 antibody or fusion protein. In some embodiments, activation of CD8+ T cells and / or NK cells can be measured, e.g., by assaying one or more markers (e.g., proportion of treated cells expressing one or more markers) of proliferation (e.g., Ki67), IL-2Rȕ / Ȗ downstream signaling, and / or STAT5 downstream signaling. Exemplary fusion proteins

[0138] In some embodiments, a fusion protein of the present disclosure comprises one, two, or all three polypeptides shown for a single fusion protein in Table 5. In some embodiments, a fusion protein of the present disclosure comprises two light chains, a heavy chain comprising an IL-2 fusion, and a heavy chain not comprising an IL-2 fusion for a single fusion protein in Table 5. As is known in the art, the C-terminal lysine of some antibody heavy chain species may be cleaved off in some fraction of molecules. Therefore, in some embodiments, a fusion protein of the present disclosure comprises two light chains, a heavy chain comprising an IL-2 fusion, and a heavy chain not comprising an IL-2 fusion for a single fusion protein in Table 5, wherein the heavy chain not comprising the IL-2 fusion comprises the sequence of SEQ ID Nos:158, 161, 164, 167, 170, 173, 176, 189, 300, 304, 308, 312, 326, 320, 324, 328, 332, 336, 340, 344, 348, or 352 for the respective fusion protein. In some embodiments, a fusion protein of the present disclosure comprises two light chains, a heavy chain comprising an IL-2 fusion, and a heavy chain not comprising an IL-2 fusion for a single fusion protein in Table 5, wherein the heavy chain not comprising the IL-2 fusion comprises the sequence of SEQ ID Nos:217-224, 301, 305, 309, 313, 317, 321, 325, 329, 333, 337, 341, 345, 349, or 353 for the respective fusion protein. In some embodiments, the present disclosure provides a plurality of fusion proteins of the present disclosure (eg in a mixture) wherein each fusion protein of the plurality comprises twolight chains, a heavy chain comprising an IL-2 fusion, and a heavy chain not comprising an IL-2 fusion for a single fusion protein in Table 5, wherein the heavy chain not comprising the IL-2 fusion comprises the sequence of SEQ ID Nos:158, 161, 164, 167, 170, 173, 176, 189, 300, 304, 308, 312, 326, 320, 324, 328, 332, 336, 340, 344, 348, or 352 for the respective fusion protein, or the sequence of SEQ ID Nos:217-224, 301, 305, 309, 313, 317, 321, 325, 329, 333, 337, 341, 345, 349, or 353 for the respective fusion protein, or the plurality comprises a mixture of species representing cleaved (e.g., comprising the sequence of SEQ ID Nos:158, 161, 164, 167, 170, 173, 176, 189, 300, 304, 308, 312, 326, 320, 324, 328, 332, 336, 340, 344, 348, or 352 for the respective fusion protein) and uncleaved (e.g., comprising the sequence of SEQ ID Nos: 217- 224, 301, 305, 309, 313, 317, 321, 325, 329, 333, 337, 341, 345, 349, or 353 for the respective fusion protein) species.

[0139] For example, in some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:158. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:161. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:164. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:167. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:170. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:173. In some embodiments, a fusionprotein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:176. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:189. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:300. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:304. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:308. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:312. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:316. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:320. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:324. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the aminoacid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:328. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:336. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:340. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:344. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:348. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:352.

[0140] In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:217. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:218. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:219. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:220. In someembodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:221. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:222. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:223. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:224. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:301. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:305. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:309. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:313. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:317. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chaincomprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:321. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:325. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:329. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:333. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:337. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:341. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:345. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:349. In some embodiments, a fusion protein of the present disclosure comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:353.

[0141] In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ IDNO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:158 or 217. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:161 or 218. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:164 or 219. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:167 or 220. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:170 or 221. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:173 or 222. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:176 or 223. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:189 or 224. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chaincomprising the amino acid sequence of SEQ ID NO:300 or 301. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:304 or 305. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:308 or 309. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:312 or 313. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:316 or 317. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:320 or 321. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:324 or 325. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:328 or 329. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequenceof SEQ ID NO:332 or 333. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:336 or 337. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:340 or 341. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:344 or 345. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:348 or 349. In some embodiments, the present disclosure provides a mixture of fusion protein species, wherein each species comprises one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:352 or 353.

[0142] In some embodiments, the present disclosure provides a fusion protein comprising two heavy chain sequences and two light chain sequences of a single fusion protein listed in Table 5, wherein one of the heavy chain sequences has an IL2 fusion and the other heavy chain sequence is without an IL2 fusion, and wherein the two light chain sequences are identical. In some embodiments, the heavy chain sequence without an IL2 fusion comprises a lysine at the C terminus. In some embodiments, the fusion protein is of format A shown in FIG.7. For example, in some embodiments, the fusion protein comprises four polypeptide chains, wherein (1) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:336, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; (2) the first polypeptide chain comprisesthe amino acid sequence of SEQ ID NO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:337, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; (3) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:340, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:338; or (4) the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:341, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:338. Table 5. Anti-CD8:IL2 fusion protein sequencesProduction of antibodies and fusion proteins

[0143] Further provided herein are polynucleotides (e.g., isolated polynucleotides) encoding any of the antibodies, antibody fragments, and fusion proteins described herein. Further provided herein are vectors (e.g., expression vectors) encoding any of the antibodies, antibody fragments, and fusion proteins described herein.

[0144] Further provided herein are host cells (e.g., isolated host cells or host cell lines) comprising any of the polynucleotides or vectors described herein.

[0145] Further provided herein are methods of producing any of the antibodies, antibody fragments, and fusion proteins described herein. In some embodiments, the methods comprise culturing a host cell of the present disclosure under conditions suitable for production of the antibody, antibody fragment, or fusion protein. In some embodiments, the methods further comprise recovering the antibody, antibody fragment, or fusion protein.

[0146] Antibodies, antibody fragments, and fusion proteins may be produced using recombinant methods, e.g., as exemplified infra. In some embodiments, nucleic acid encoding the antibody / fusion protein can be isolated and inserted into a replicable vector for further cloning or for expression. DNA encoding the antibody / fusion protein may be readily isolated and sequenced using conventional procedures (e.g., via oligonucleotide probes capable of binding specifically to genes encoding the heavy and light chains of the antibody / fragment). Many vectors are known in the art; vector components generally include, but are not limited to, one or more of the following: a signal sequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence. Suitable host cells for cloning or expressing the DNA in the vectors herein are the prokaryote, yeast, or higher eukaryote cells. When using recombinant techniques, the antibody / fusion protein can be produced intracellularly, in the periplasmic space, or directly secreted into the medium. If the antibody / fragment is produced intracellularly, the particulate debris, either host cells or lysed fragments, are removed, for example, by centrifugation or ultrafiltration. Where the antibody / fusion protein is secreted into the medium, supernatants from such expression systems are generally first concentrated using a commercially available protein concentration filter.Pharmaceutical compositions

[0147] In some embodiments, a fusion protein of the present disclosure is part of a pharmaceutical composition, e.g., including the fusion protein and one or more pharmaceutically acceptable carriers. Pharmaceutical compositions and formulations as described herein can be prepared by mixing the active ingredients (such as a fusion protein) having the desired degree of purity with one or more optional pharmaceutically acceptable carriers (Remington’s Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)), in the form of lyophilized formulations or aqueous solutions. Pharmaceutically acceptable carriers are generally nontoxic to recipients at the dosages and concentrations employed, and include, but are not limited to: buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives; low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g. Zn-protein complexes); and / or non-ionic surfactants such as polyethylene glycol (PEG). In some embodiments, a fusion protein of the present disclosure is lyophilized. Methods and Kits

[0148] Certain aspects of the present disclosure relate to methods of treating cancer or chronic infection. In some embodiments, the methods comprise administering an effective amount of a fusion protein or antibody, or a pharmaceutical composition comprising the fusion protein or antibody and a pharmaceutically acceptable carrier, to a patient. In some embodiments, the patient in need of said treatment has been diagnosed with cancer.

[0149] In some embodiments, the fusion protein or composition is administered in combination with a T cell therapy, cancer vaccine, chemotherapeutic agent, or immune checkpoint inhibitor (ICI). In some embodiments, the chemotherapeutic agent is a kinase inhibitor, antimetabolite, cytotoxin or cytostatic agent, anti-hormonal agent, platinum-based chemotherapeutic agent, methyltransferase inhibitor, antibody, or anti-cancer peptide. In some embodiments, the immune checkpoint inhibitor targets PD-L1, PD-1, CTLA-4, CEACAM, LAIR1, CD160, 2B4, CD80, CD86, CD276, VTCN1, HVEM, KIR, A2AR, MHC class I, MHC class II GALS adenosine TGFR OX40 CD137 CD40 CD47 TREM1 TREM2 HLA GCCR4, CCR8, CD39, CD73, IDO, CSF1R, TIM-3, BTLA, VISTA, LAG-3, TIGIT, IDO, MICA / B, LILRB4, SIGLEC-15, or arginase, including without limitation an inhibitor of PD-1 (e.g., an anti-PD-1 antibody), PD-L1 (e.g., an anti-PD-L1 antibody), or CTLA-4 (e.g., an anti- CTLA-4 antibody).

[0150] Examples of anti-PD-1 antibodies include, without limitation, pembrolizumab, nivolumab, cemiplimab, zimberelimab (Arcus), sasanlimab (Pfizer), JTX-4014, spartalizumab (PDR001; Novartis), camrelizumab (SHR1210; Jiangsu HengRui Medicine), sintilimab (IBI308; Innovent and Eli Lilly), tislelizumab (BGB-A317), toripalimab (JS 001), dostarlimab (TSR-042, WBP-285), INCMGA00012 (MGA012), AMP-224, and AMP-514 (MEDI0680). Examples of anti-PD-L1 antibodies include, without limitation, atezolizumab, avelumab, durvalumab, KN035, and CK-301 (Checkpoint Therapeutics). Examples of PD-L1 inhibitors (non-antibody based) include, without limitation, AUNP12, CA-170, and BMS-986189. Examples of anti-CTLA-4 antibodies include, without limitation, ipilimumab, tremelimumab, BMS-986218, BMS-986249, BMS-986288, HBM4003, ONC-392, KN044, ADG116, ADU-1604, AGEN1181, AGEN1884, MK-1308, and REGN4659.

[0151] Examples of T cell therapies include, without limitation, CD4+ or CD8+ T cell-based therapies, adoptive T cell therapies, chimeric antigen receptor (CAR)-based T cell therapies, tumor-infiltrating lymphocyte (TIL)-based therapies, autologous T cell therapies, allogeneic T cell therapies, and therapies with T cells bearing a transduced TCR. Exemplary cancer vaccines include, without limitation, dendritic cell vaccines, vaccines comprising one or more polynucleotides encoding one or more cancer antigens, and vaccines comprising one or more cancer antigenic peptides.

[0152] Certain aspects of the present disclosure relate to methods of expanding T cells, e.g., ex vivo. In some embodiments, the methods comprise contacting one or more T cells, e.g., ex vivo with an effective amount of the ...

Claims

CLAIMS What is claimed is:

1. A human or humanized antibody or antigen-binding fragment thereof, wherein the antibody or fragment specifically binds human CD8b and / or human CD8ab with at least 10-fold higher affinity than its binding to human CD8a and / or human CD8aa.

2. The antibody or fragment of claim 1, wherein the antibody or fragment binds to a cell expressing a human CD8ab heterodimer on its surface with an EC50 that is less than 1000nM.

3. The antibody or fragment of claim 1 or claim 2, wherein the antibody or fragment binds human CD8+ T cells.

4. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

18.

5. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

18.

6. The antibody or fragment of claim 4 or claim 5, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

63.

7. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab wherein the antibody or fragment comprises a heavy chain variable (VH) domainand a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

24.

8. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

24.

9. The antibody or fragment of claim 7 or claim 8, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

65.

10. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

30.

11. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ IDNO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

30.

12. The antibody or fragment of claim 10 or claim 11, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

67.

13. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

36.

14. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

36.

15. The antibody or fragment of claim 13 or claim 14, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

69.

16. A human antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acidsequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

42.

17. A human antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

42.

18. The antibody or fragment of claim 16 or claim 17, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

71.

19. A human antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

48.

20. A human antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequenceof SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

48.

21. The antibody or fragment of claim 19 or claim 20, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

73.

22. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

6.

23. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

6.

24. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:182.

25. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

182.

26. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises: a CDR-H1 comprising the amino acid sequence of X1X2AIS, wherein X1 is S, K, G, N, R, D, T, or G, and wherein X2 is Y, L, H, or F (SEQ ID NO:259), a CDR-H2 comprising the amino acid sequence of X1X2X3PX4X5X6X7X8X9YX10QKFX11G, wherein X1is G or H, X2is I or F, X3is I, N, or M, X4is G, N, H, S, R, I, or A, X5is A, N, H, S, T, F, or Y, X6is A, D, or G, X7is T, E, K, V, Q, or A, X8is A or T, X9is N or K, X10is A or N, and X11is Q or T (SEQ ID NO:260), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1 is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3 is A, L, P, or Y, X4 is I or L, X5 is R, A, Q, or S, X6 is A or D, and X7 is D, E, A, or S (SEQ ID NO:261); and wherein the VL domain comprises: a CDR-L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1is R or G, X2is A or T, X3is Q or E, X4is E, N, T, S, A, K, D, G, R, or Q, X5is Y or S, and X6is A or V (SEQ ID NO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1 is A or S, X2 is T, S, E, Q, or D, X3 is N, R, A, E, or H, X4 is Q or A, and X5 is S or D (SEQ ID NO:263), anda CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1is S, N, D, Q, A, or E, X2is T, I, or S, X3is Y, L, or F, X4is D, G, T, E, Q, A, or Y, and X5 is A, T, R, S, K, or Y (SEQ ID NO:264).

27. The antibody of claim 26, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

228.

28. The antibody of claim 26, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

236.

29. The antibody of claim 26, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

228.

30. The antibody of any one of claims 26-29, wherein the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKASGGTFS (SEQ ID NO:274), a FW-2 comprising the sequence WVRQAPGQGLEWMG (SEQ ID NO:275), a FW-3 comprising the sequence RVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:276), and a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277); and wherein the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

31. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises: a CDR-H1 comprising the amino acid sequence of GX1X2FX3X4X5, wherein X1 is G, Y, S, or A, X2 is T, S, G, R, N, or H, X3 is S, T, R, H, Y, G, or P, X4 is S, K, G, N, R, D, T, or G, and X5is Y, L, H, or F (SEQ ID NO:265), a CDR-H2 comprising the amino acid sequence of X1PX2X3X4X5, wherein X1is I, N, or M, X2is G, N, H, S, R, I, or A, X3is A, N, H, S, T, F, or Y, X4is A, D, or G, and X5is T, E, K, V, Q, or A (SEQ ID NO:266), and a CDR-H3 comprising the amino acid sequence of X1X2X3GX4X5LFX6X7, wherein X1 is D or A, X2 is A, G, E, R, Y, K, N, Q, L, or F, X3 is A, L, P, or Y, X4 is I or L, X5 is R, A, Q, or S, X6 is A or D, and X7 is D, E, A, or S (SEQ ID NO:267); and wherein the VL domain comprises: a CDR-L1 comprising the amino acid sequence of X1X2SX3X4IX5GX6LN, wherein X1is R or G, X2is A or T, X3is Q or E, X4is E, N, T, S, A, K, D, G, R, or Q, X5is Y or S, and X6is A or V (SEQ ID NO:262), a CDR-L2 comprising the amino acid sequence of GX1X2X3LX4X5, wherein X1is A or S, X2 is T, S, E, Q, or D, X3 is N, R, A, E, or H, X4 is Q or A, and X5 is S or D (SEQ ID NO:263), and a CDR-L3 comprising the amino acid sequence of QX1X2X3X4X5PWT, wherein X1 is S, N, D, Q, A, or E, X2 is T, I, or S, X3 is Y, L, or F, X4 is D, G, T, E, Q, A, or Y, and X5is A, T, R, S, K, or Y (SEQ ID NO:264).

32. The antibody of claim 31, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

228.

33. The antibody of claim 31, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238 a CDR H2 comprising the amino acid sequence ofSEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

236.

34. The antibody of claim 31, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

228.

35. The antibody of any one of claims 31-34, wherein the VH domain further comprises a FW-1 comprising the sequence QVQLVQSGAEVKKPGSSVKVSCKAS (SEQ ID NO:278), a FW-2 comprising the sequence AISWVRQAPGQGLEWMGGI (SEQ ID NO:279), a FW-3 comprising the sequence ANYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCAR (SEQ ID NO:280), and a FW-4 comprising the sequence WGQGTLVTVSS (SEQ ID NO:277); and wherein the VL domain further comprises a FW-1 comprising the sequence DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO:289), a FW-2 comprising the sequence WYQQKPGKAPKLLIY (SEQ ID NO:290), a FW-3 comprising the sequence GVPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO:291), and a FW-4 comprising the sequence FGGGTKVEIK (SEQ ID NO:292).

36. The antibody of claim 26 or claim 31, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

246.

37. The antibody of claim 26 or claim 31, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252; optionally wherein the VH domain comprises the amino acid sequence of SEQ ID NO:251, and the VL domain comprises the amino acid sequence of SEQ ID NO:252.

38. The antibody of claim 26 or claim 31, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

254.

39. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises: a CDR-H1 comprising the amino acid sequence of X1YX2MS, wherein X1is S, D, E, A, or Q and X2is A, G, or T (SEQ ID NO:268), a CDR-H2 comprising the amino acid sequence of DIX1X2X3GX4X5TX6YADSVKG, wherein X1 is T, N, S, Q, E, H, R, or A, X2 is Y, W, F, or H, X3 is A, S, Q, E, or T, X4 is G or E, X5 is S or I, and X6 is A or G (SEQ ID NO:269), and a CDR-H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1is S or A, X2is N, H, A, D, L, Q, Y, or R, X3is A, N, S, or G, X4is A, V, R, E, or S, X5is D or S, X6is D, N, Q, E, S, T, or L, X7is L, F, or M, and X8is I, Y, or V (SEQ ID NO:270); and wherein the VL domain comprises: a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42).

40. The antibody of claim 39, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:

231.

41. The antibody of claim 39, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237 and a CDR H3 comprising the amino acid sequence of SEQ ID NO:23142. The antibody of any one of claims 39-41, wherein the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAASGFTFS (SEQ ID NO:281), a FW-2 comprising the sequence WVRQAPGKGLEWVS (SEQ ID NO:282), a FW-3 comprising the sequence RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:283), and a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285); and wherein the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

43. A humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain; wherein the VH domain comprises: a CDR-H1 comprising the amino acid sequence of GFTFX1X2Y, wherein X1is S, D, E, Q, S, or A and X2is S, D, E, A, or Q (SEQ ID NO:271), a CDR-H2 comprising the amino acid sequence of X1X2X3GX4X5, wherein X1is T, N, S, Q, E, H, R or A, X2is Y, W, F, or H, X3is A, S, Q, E, or T, X4is G or E, and X5is S or I (SEQ ID NO:272), and a CDR-H3 comprising the amino acid sequence of X1X2X3YX4WX5X6AX7DX8, wherein X1 is S or A, X2 is N, H, A, D, L, Q, Y, or R, X3 is A, N, S, or G, X4 is A, V, R, E, or S, X5 is D or S, X6 is D, N, Q, E, S, T, or L, X7 is L, F, or M, and X8 is I, Y, or V (SEQ ID NO:273); and wherein the VL domain comprises: a CDR-L1 comprising the amino acid sequence of RASQSVSSNLA (SEQ ID NO:40), a CDR-L2 comprising the amino acid sequence of GASSRAT (SEQ ID NO:41), and a CDR-L3 comprising the amino acid sequence of QQYGSSPPVT (SEQ ID NO:42).

44. The antibody of claim 43, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:

242.

45. The antibody of claim 43, wherein the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:

242.

46. The antibody of any one of claims 43-45, wherein the VH domain further comprises a FW-1 comprising the sequence EVQLVESGGGLVQPGGSLRLSCAAS (SEQ ID NO:286), a FW-2 comprising the sequence AMSWVRQAPGKGLEWVSDI (SEQ ID NO:287), a FW-3 comprising the sequence TAYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:288), and a FW-4 comprising the sequence WGQGTMVTVSS (SEQ ID NO:284) or WGQGTLVTVSS (SEQ ID NO:285); and wherein the VL domain further comprises a FW-1 comprising the sequence EIVLTQSPGTLSLSPGERATLSC (SEQ ID NO:293), a FW-2 comprising the sequence WYQQKPGQAPRLLIY (SEQ ID NO:294), a FW-3 comprising the sequence GIPDRFSGSGSGTDFTLTISRLEPEDFAVYYC (SEQ ID NO:295), and a FW-4 comprising the sequence FGQGTKVEIK (SEQ ID NO:296).

47. The antibody of claim 39 or claim 43, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

248.

48. The antibody of claim 39 or claim 43, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250; optionally wherein the VH domain comprises the amino acid sequence of SEQ ID NO:249, and the VL domain comprises the amino acid sequence of SEQ ID NO:

250.

49. The antibody of claim 39 or claim 43, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256.

50. The antibody of claim 39 or claim 43, wherein the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257; and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:

258.

51. The antibody of any one of claims 1-50, wherein the antibody is a multispecific antibody.

52. The antibody of claim 51, wherein the antibody is a bispecific antibody.

53. A fusion protein, comprising: (a) a first moiety comprising the antibody or fragment according to any one of claims 1- 52; and (b) a second moiety comprising a cytokine, chemokine, or growth factor; wherein the first moiety is fused to the second moiety directly or via a linker.

54. A fusion protein, comprising: (a) a first moiety comprising a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VLdomain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ IDNO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40,a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; and (b) a second moiety comprising a cytokine, chemokine, or growth factor; wherein the first moiety is fused to the second moiety directly or via a linker. A fusion protein, comprising: (a) a first moiety comprising a human or humanized antibody or antigen-binding fragment thereof that specifically binds CD8b and / or CD8ab, wherein the antibody or fragment comprises a heavy chain variable (VH) domain and a light chain variable (VL) domain, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR L1 comprising the amino acid sequence of SEQ ID NO:34 aCDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16,a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; and (b) a second moiety comprising a cytokine, chemokine, or growth factor; wherein the first moiety is fused to the second moiety directly or via a linker.

56. The fusion protein of any one of claims 53-55, wherein the second moiety induces activation of CD8+ T cells.

57. The fusion protein of claim 56, wherein the fusion protein induces activation of cells expressing a human CD8ab heterodimer with at least 10-fold higher potency than activation of cells expressing a human CD8aa homodimer.

58. The fusion protein of claim 56, wherein the fusion protein induces activation of CD8+ T cells with at least 10-fold higher potency than activation of NK cells.

59. The fusion protein of claim 57 or claim 58, wherein potency of activation is measured by EC50, as assessed by cell proliferation.

60. The fusion protein of any one of claims 53-59, wherein the first moiety comprises two antibody heavy chain polypeptides comprising a structure according to formula [I], from N- terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I] and two antibody light chain polypeptides comprising a structure according to formula [II], from N-terminus to C-terminus: VL-CL [II] wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of one of the two CH3 domains.

61. The fusion protein of any one of claims 53-59, wherein the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N- terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III],wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the second antibody heavy chain polypeptide.

62. The fusion protein of any one of claims 53-59, wherein the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N- terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III], wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain; and wherein the C-terminus of the second moiety is fused to the N-terminus of the hinge domain of the second antibody heavy chain polypeptide.

63. The fusion protein of any one of claims 53-59, wherein the first moiety comprises a first antibody heavy chain polypeptide comprising a structure according to formula [I], from N- terminus to C-terminus: VH-CH1-hinge-CH2-CH3 [I], an antibody light chain polypeptide comprising a structure according to formula [II], from N- terminus to C-terminus: VL-CL [II], and a second antibody heavy chain polypeptide comprising a structure according to formula [III], from N-terminus to C-terminus: hinge-CH2-CH3 [III],wherein VH is the VH domain, wherein CH1 is an antibody CH1 domain, wherein hinge is an antibody hinge domain, wherein CH2-CH3 is an antibody Fc domain, wherein VL is the VL domain, and wherein CL is an antibody constant light chain domain; and wherein the N-terminus of the second moiety is fused to the C-terminus of the CH3 domain of the first antibody heavy chain polypeptide.

64. The fusion protein of claim 60, wherein: the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain of both antibody light chain polypeptidescomprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182;the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acidsequence of SEQ ID NO:231; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:

42.

65. The fusion protein of claim 60, wherein: the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR L1 comprising the amino acid sequence of SEQ ID NO:34 a CDR L2comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182;the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain of both antibody heavy chain polypeptides comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acidsequence of SEQ ID NO:242; and wherein the VL domain of both antibody light chain polypeptides comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:

42.

66. The fusion protein of claim 60, 64, or 65, wherein: the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:63; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:62, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:63; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:64, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:65; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:66, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:67; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90% at least 95% at least 99% or 100% identical to thesequence of SEQ ID NO:68, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:68, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:69; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:71; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:70, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:71; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:72, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:73; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:186; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:185, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:186;the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:245, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:246; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:251, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:252; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:253, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:254; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ IDNO:247, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:248; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:249, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:250; the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:255, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:256; or the VH domain of both antibody heavy chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257, and wherein the VL domain of both antibody light chain polypeptides comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258; optionally the VH domain of both antibody heavy chain polypeptides comprises the amino acid sequence of SEQ ID NO:257, and the VL domain of both antibody light chain polypeptides comprises the amino acid sequence of SEQ ID NO:

258.

67. The fusion protein of any one of claims 61-63, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:13, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:14, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR L1 comprising the amino acid sequence of SEQ ID NO:16 aCDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:19, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:20, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:25, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:26, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:28, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:31, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:32, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:37, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:38, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:43, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:44, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, aCDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:1, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:2, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:177, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:178, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:226, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:227; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:230, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ IDNO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:225, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:232, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:229, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:237, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:231; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

42.

68. The fusion protein of any one of claims 61-63, wherein: the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:51, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:15; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:18; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:53, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:21; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:22, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:23, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:24; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:27; and wherein the VL domain comprises a CDR L1 comprising the amino acid sequence of SEQ ID NO:28 aCDR-L2 comprising the amino acid sequence of SEQ ID NO:29, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:30; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:54, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:52, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:33; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:34, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:35, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:36; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:56, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:39; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:55, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:57, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:45; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:46, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:47, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:48; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:49, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:50, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:3; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:4, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:5, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:6; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:183, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:184, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:179; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ IDNO:180, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:181, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:182; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:239, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:241, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:42; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:234, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:235, and a CDR- L3 comprising the amino acid sequence of SEQ ID NO:236; the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:238, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:243, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:233; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:16, a CDR-L2 comprising the amino acid sequence of SEQ ID NO:17, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:228; or the VH domain comprises a CDR-H1 comprising the amino acid sequence of SEQ ID NO:240, a CDR-H2 comprising the amino acid sequence of SEQ ID NO:244, and a CDR-H3 comprising the amino acid sequence of SEQ ID NO:242; and wherein the VL domain comprises a CDR-L1 comprising the amino acid sequence of SEQ ID NO:40,a CDR-L2 comprising the amino acid sequence of SEQ ID NO:41, and a CDR-L3 comprising the amino acid sequence of SEQ ID NO:

42.

69. The fusion protein of any one of claims 61-63, 67 and 68, wherein: the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:62, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:63; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:62, and the VL domain comprises the amino acid sequence of SEQ ID NO:63; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:64, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:65; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:64, and the VL domain comprises the amino acid sequence of SEQ ID NO:65; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:66, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:67; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:66, and the VL domain comprises the amino acid sequence of SEQ ID NO:67; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:68, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:69; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:68, and the VL domain comprises the amino acid sequence of SEQ ID NO:69; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:70, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99% or 100% identical to the sequence of SEQ ID NO:71; optionally the VH domaincomprises the amino acid sequence of SEQ ID NO:70, and the VL domain comprises the amino acid sequence of SEQ ID NO:71; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:72, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:73; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:72, and the VL domain comprises the amino acid sequence of SEQ ID NO:73; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:186; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:185, and the VL domain comprises the amino acid sequence of SEQ ID NO:186; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:245, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:246; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:245, and the VL domain comprises the amino acid sequence of SEQ ID NO:246; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:251, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:252; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:251, and the VL domain comprises the amino acid sequence of SEQ ID NO:252; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:253, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:254; optionally, the VHdomain comprises the amino acid sequence of SEQ ID NO:253, and the VL domain comprises the amino acid sequence of SEQ ID NO:254; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:247, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:248; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:247, and the VL domain comprises the amino acid sequence of SEQ ID NO:248; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:249, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:250; optionally the VH domain comprises the amino acid sequence of SEQ ID NO:249, and the VL domain comprises the amino acid sequence of SEQ ID NO:250; the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:255, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:256; or optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:255, and the VL domain comprises the amino acid sequence of SEQ ID NO:256; or the VH domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:257, and wherein the VL domain comprises an amino acid sequence that is at least 90%, at least 95%, at least 99%, or 100% identical to the sequence of SEQ ID NO:258; optionally, the VH domain comprises the amino acid sequence of SEQ ID NO:257, and the VL domain comprises the amino acid sequence of SEQ ID NO:

258.

70. The fusion protein of any one of claims 60-69, wherein one or both of the antibody heavy chain polypeptides comprise(s) the following amino acid substitutions: L234A, L235A, and G237A, numbering according to EU index.

71. The fusion protein of any one of claims 60-70, wherein a first of the antibody heavy chain polypeptides comprises amino acid substitutions Y349C and T366W and a second of theantibody heavy chain polypeptides comprises amino acid substitutions S354C, T366S, L368A and Y407V, numbering according to EU index.

72. The fusion protein of any one of claims 53-59, wherein the first moiety comprises one or two antibody heavy chain polypeptides and one or two antibody light chain polypeptides.

73. The fusion protein of any one of claims 53-59, wherein the first moiety comprises a single chain antibody or single chain variable fragment (scFv).

74. The fusion protein of any one of claims 53-59, wherein the first moiety comprises a VHH antibody.

75. The fusion protein of any one of claims 53-74, wherein the second moiety comprises an IL-2 polypeptide.

76. The fusion protein of claim 75, wherein the IL-2 polypeptide is a mutant IL-2 polypeptide comprising one or more mutations relative to a human IL-2 polypeptide comprising the sequence of77. The fusion protein of claim 76, wherein the mutant IL-2 polypeptide has a binding affinity to IL-2RD that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2Rɲ^ 78. The fusion protein of claim 77, wherein the mutant IL-2 polypeptide has a binding affinity to IL-2Rɴ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2Rɴ; and / or wherein the mutant IL-2 polypeptide has a binding affinity to IL-2RȖ that is reduced by 50% or more, compared to binding affinity of a wild-type IL-2 polypeptide comprising the sequence of SEQ ID: 81 for IL-2RȖ.

79. The fusion protein of any one of claims 63-78, wherein the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one, two, three, four, or five amino acid substitutions relative to SEQ ID NO:81, and wherein the one, two, three, four, or five substitution(s) comprise substitution(s) at positions of SEQ ID NO:81 selected from the group consisting of: Q11, H16,L18, L19, D20, Q22, R38, F42, K43, Y45, E62, P65, E68, V69, L72, D84, S87, N88, V91, I92, T123, Q126, S127, I129, and S130.

80. The fusion protein of claim 79, wherein the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E and F42A; R38D and F42A; F42A and E62Q; R38A and F42K; R38E, F42A, and N88S; R38E, F42A, and N88A; R38E, F42A, and N88G; R38E, F42A, and N88R; R38E, F42A, and N88T; R38E, F42A, and N88D; R38E, F42A, and V91E; R38E, F42A, and D84H; R38E, F42A, and D84K; R38E, F42A, and D84R; H16D, R38E and F42A; H16E, R38E and F42A; R38E, F42A and Q126S; R38D, F42A and N88S; R38D, F42A and N88A; R38D, F42A and N88G; R38D, F42A and N88R; R38D, F42A and N88T; R38D, F42A and N88D; R38D, F42A and V91E; R38D, F42A, and D84H; R38D, F42A, and D84K; R38D, F42A, and D84R; H16D, R38D and F42A; H16E, R38D and F42A; R38D, F42A and Q126S; R38A, F42K, and N88S; R38A, F42K, and N88A; R38A, F42K, and N88G; R38A, F42K, and N88R; R38A, F42K, and N88T; R38A, F42K, and N88D; R38A, F42K, and V91E; R38A, F42K, and D84H; R38A, F42K, and D84K; R38A, F42K, and D84R; H16D, R38A, and F42K; H16E, R38A, and F42K; R38A, F42K, and Q126S; F42A, E62Q, and N88S; F42A, E62Q, and N88A; F42A, E62Q, and N88G; F42A, E62Q, and N88R; F42A, E62Q, and N88T; F42A, E62Q, and N88D; F42A, E62Q, and V91E; F42A, E62Q, and D84H; F42A, E62Q, and D84K; and F42A, E62Q, and D84R.

81. The fusion protein of claim 79, wherein the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with a further amino acid substitution relative to SEQ ID NO:81 at position C125.

82. The method of claim 81, wherein the IL-2 polypeptide comprises the sequence of SEQ ID NO:81 with one of the following sets of amino acid substitutions (relative to the sequence of SEQ ID NO:81): R38E, F42A, and C125A; R38D, F42A , and C125A; F42A, E62Q, and C125A; R38A, F42K, and C125A; R38E, F42A, N88S, and C125A; R38E, F42A, N88A, and C125A; R38E, F42A, N88G, and C125A; R38E, F42A, N88R, and C125A; R38E, F42A, N88D, and C125A; R38E, F42A, N88T, and C125A; R38E, F42A, V91E, and C125A; R38E, F42A, D84H, and C125A; R38E, F42A, D84K, and C125A; R38E, F42A, D84R, and C125A; H16D, R38E, F42A, and C125A; H16E, R38E, F42A, and C125A; R38E, F42A, C125A and Q126S; R38D, F42A, N88S, and C125A; R38D, F42A, N88A, and C125A; R38D, F42A, N88G, andC125A; R38D, F42A, N88R, and C125A; R38D, F42A, N88T, and C125A; R38D, F42A, N88D, and C125A; R38D, F42A, V91E, and C125A; R38D, F42A, D84H, and C125A; R38D, F42A, D84K, and C125A; R38D, F42A, D84R, and C125A; H16D, R38D, F42A, and C125A; H16E, R38D, F42A, and C125A; R38D, F42A , C125A, and Q126S; R38A, F42K, N88S, and C125A; R38A, F42K, N88G, and C125A; R38A, F42K, N88R, and C125A; R38A, F42K, N88T, and C125A; R38A, F42K, N88D, and C125A; R38A, F42K, N88A, and C125A; R38A, F42K, V91E, and C125A; R38A, F42K, D84H, and C125A; R38A, F42K, D84K, and C125A; R38A, F42K, D84R, and C125A; H16D, R38A, F42K, and C125A; H16E, R38A, F42K, and C125A; R38A, F42K, C125A and Q126S; F42A, E62Q, N88S, and C125A; F42A, E62Q, N88A, and C125A; F42A, E62Q, N88G, and C125A; F42A, E62Q, N88R, and C125A; F42A, E62Q, N88T, and C125A; F42A, E62Q, N88D, and C125A; F42A, E62Q, V91E, and C125A; F42A, E62Q, and D84H, and C125A; F42A, E62Q, and D84K, and C125A; F42A, E62Q, and D84R, and C125A; H16D, F42A, and E62Q, and C125A; H16E, F42A, E62Q, and C125A; F42A, E62Q, C125A and Q126S; F42A, N88S, and C125A; F42A, N88A, and C125A; F42A, N88G, and C125A; F42A, N88R, and C125A; F42A, N88T, and C125A; F42A, N88D, and C125A;F42A, V91E, and C125A; F42A, D84H, and C125A; F42A, D84K, and C125A; F42A, D84R, and C125A; H16D, F42A, and C125A; H16E, F42A, and C125A; and F42A, C125A and Q126S.

83. The fusion protein of any one of claims 63-78, wherein the IL-2 polypeptide comprises the sequence84. The fusion protein of any one of claims 75-78, wherein the IL-2 polypeptide comprises a sequence selected from the group consisting of SEQ ID NOs: 80, 85-155, 190-216, 297, and 354-383.

85. The fusion protein of any one of claims 53-74, wherein the second moiety comprises a polypeptide that induces signaling via IL2REJ^86. The fusion protein of any one of claims 53-74, wherein the second moiety comprises an IL-21 polypeptide.

87. The fusion protein of any one of claims 60-86, wherein one or both of the antibody Fc domains comprise(s) human IgG1 Fc domains with the following amino acid substitutions: L234A, L235A, and G237A, numbering according to EU index; optionally said one or both of the antibody Fc domains do not have the C-terminal lysine.

88. The fusion protein of any one of claims 60-87, wherein a first of the two Fc domains comprises a human IgG1 Fc domain with amino acid substitutions Y349C and T366W, and a second of the two Fc domain comprises a human IgG1 Fc domain with amino acid substitutions S354C, T366S, L368A and Y407V, numbering according to EU index; optionally said one or both of the antibody Fc domains do not have the C-terminal lysine.

89. The fusion protein of any one of claims 53-88, wherein the linker comprises the sequence (GGGS)xGn (SEQ ID NO:74), (GGGGS)xGn (SEQ ID NO:75), or (GGGGGS)xGn (SEQ ID NO:76), S(GGGS)xGn (SEQ ID NO:386), S(GGGGS)xGn (SEQ ID NO:387), or:388), wherein x=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and wherein n=0, 1, 2 or 3.

90. The fusion protein of any one of claims 53-88, wherein the linker comprises the sequenceNO:389).

91. The fusion protein of any one of claims 53-88, wherein the fusion protein comprises: one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:158; one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:161; one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:164; one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:167;one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:170; one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:173; one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:176; one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:189; one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:300; one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:304; one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:308; one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:312; one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:316; one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:320;one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:324; one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:328; one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:332; one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:336; one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:340; one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:344; one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:348; one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:352; one or two light chains comprising the amino acid sequence of SEQ ID NO:156, a heavy chain comprising the amino acid sequence of SEQ ID NO:157, and a heavy chain comprising the amino acid sequence of SEQ ID NO:217; one or two light chains comprising the amino acid sequence of SEQ ID NO:159, a heavy chain comprising the amino acid sequence of SEQ ID NO:160, and a heavy chain comprising the amino acid sequence of SEQ ID NO:218;one or two light chains comprising the amino acid sequence of SEQ ID NO:162, a heavy chain comprising the amino acid sequence of SEQ ID NO:163, and a heavy chain comprising the amino acid sequence of SEQ ID NO:219; one or two light chains comprising the amino acid sequence of SEQ ID NO:165, a heavy chain comprising the amino acid sequence of SEQ ID NO:166, and a heavy chain comprising the amino acid sequence of SEQ ID NO:220; one or two light chains comprising the amino acid sequence of SEQ ID NO:168, a heavy chain comprising the amino acid sequence of SEQ ID NO:169, and a heavy chain comprising the amino acid sequence of SEQ ID NO:221; one or two light chains comprising the amino acid sequence of SEQ ID NO:171, a heavy chain comprising the amino acid sequence of SEQ ID NO:172, and a heavy chain comprising the amino acid sequence of SEQ ID NO:222; one or two light chains comprising the amino acid sequence of SEQ ID NO:174, a heavy chain comprising the amino acid sequence of SEQ ID NO:175, and a heavy chain comprising the amino acid sequence of SEQ ID NO:223; one or two light chains comprising the amino acid sequence of SEQ ID NO:187, a heavy chain comprising the amino acid sequence of SEQ ID NO:188, and a heavy chain comprising the amino acid sequence of SEQ ID NO:224; one or two light chains comprising the amino acid sequence of SEQ ID NO:298, a heavy chain comprising the amino acid sequence of SEQ ID NO:299, and a heavy chain comprising the amino acid sequence of SEQ ID NO:301; one or two light chains comprising the amino acid sequence of SEQ ID NO:302, a heavy chain comprising the amino acid sequence of SEQ ID NO:303, and a heavy chain comprising the amino acid sequence of SEQ ID NO:305; one or two light chains comprising the amino acid sequence of SEQ ID NO:306, a heavy chain comprising the amino acid sequence of SEQ ID NO:307, and a heavy chain comprising the amino acid sequence of SEQ ID NO:309; one or two light chains comprising the amino acid sequence of SEQ ID NO:310, a heavy chain comprising the amino acid sequence of SEQ ID NO:311, and a heavy chain comprising the amino acid sequence of SEQ ID NO:313;one or two light chains comprising the amino acid sequence of SEQ ID NO:314, a heavy chain comprising the amino acid sequence of SEQ ID NO:315, and a heavy chain comprising the amino acid sequence of SEQ ID NO:317; one or two light chains comprising the amino acid sequence of SEQ ID NO:318, a heavy chain comprising the amino acid sequence of SEQ ID NO:319, and a heavy chain comprising the amino acid sequence of SEQ ID NO:321; one or two light chains comprising the amino acid sequence of SEQ ID NO:322, a heavy chain comprising the amino acid sequence of SEQ ID NO:323, and a heavy chain comprising the amino acid sequence of SEQ ID NO:325; one or two light chains comprising the amino acid sequence of SEQ ID NO:326, a heavy chain comprising the amino acid sequence of SEQ ID NO:327, and a heavy chain comprising the amino acid sequence of SEQ ID NO:329; one or two light chains comprising the amino acid sequence of SEQ ID NO:330, a heavy chain comprising the amino acid sequence of SEQ ID NO:331, and a heavy chain comprising the amino acid sequence of SEQ ID NO:333; one or two light chains comprising the amino acid sequence of SEQ ID NO:334, a heavy chain comprising the amino acid sequence of SEQ ID NO:335, and a heavy chain comprising the amino acid sequence of SEQ ID NO:337; one or two light chains comprising the amino acid sequence of SEQ ID NO:338, a heavy chain comprising the amino acid sequence of SEQ ID NO:339, and a heavy chain comprising the amino acid sequence of SEQ ID NO:341; one or two light chains comprising the amino acid sequence of SEQ ID NO:342, a heavy chain comprising the amino acid sequence of SEQ ID NO:343, and a heavy chain comprising the amino acid sequence of SEQ ID NO:345; one or two light chains comprising the amino acid sequence of SEQ ID NO:346, a heavy chain comprising the amino acid sequence of SEQ ID NO:347, and a heavy chain comprising the amino acid sequence of SEQ ID NO:349; or one or two light chains comprising the amino acid sequence of SEQ ID NO:350, a heavy chain comprising the amino acid sequence of SEQ ID NO:351, and a heavy chain comprising the amino acid sequence of SEQ ID NO:353.

92. A fusion protein comprising a first moiety that binds to a human CD8b and a second moiety comprising an IL2 polypeptide, wherein the fusion protein comprises four polypeptide chains, wherein: the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:336, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:334, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:335, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:337, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:334; the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:340, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:338; or the first polypeptide chain comprises the amino acid sequence of SEQ ID NO:338, the second polypeptide chain comprises the amino acid sequence of SEQ ID NO:339, the third polypeptide chain comprises the amino acid sequence of SEQ ID NO:341, and the fourth polypeptide chain comprises the amino acid sequence of SEQ ID NO:

338.

93. One or more polynucleotides encoding the antibody or fusion protein according to any one of claims 1-92.

94. One or more vectors comprising the one or more polynucleotides of claim 93.

95. The one or more vectors of claim 94, wherein the vector(s) are expression vector(s).

96. An isolated host cell comprising the one or more polynucleotides or vectors of any one of claims 93-95.

97. A method of producing an antibody or fusion protein, comprising culturing the host cell of claim 96 under conditions suitable for production of the antibody or fusion protein.

98. The method of claim 97, further comprising recovering the antibody or fusion protein from the host cell.

99. A pharmaceutical composition comprising the antibody or fusion protein according to any one of claims 1-92 and a pharmaceutically acceptable carrier.

100. The antibody or fusion protein according to any one of claims 1-92 for use as a medicament.

101. A method of treating cancer comprising administering to an individual with cancer an effective amount of the antibody or fusion protein according to any one of claims 1-92 or the composition of claim 99.

102. The method of claim 101, further comprising administering to the individual a T cell therapy, cancer vaccine, chemotherapeutic agent, or immune checkpoint inhibitor (ICI).

103. The method of claim 102, wherein the ICI is an inhibitor of PD-1, PD-L1, or CTLA-4.

104. The method of claim 102, wherein the T cell therapy comprises a chimeric antigen receptor (CAR)-based T cell therapy, a tumor-infiltrating lymphocyte (TIL)-based therapy, or a therapy with T cells bearing a transduced TCR.

105. The antibody or fusion protein according to any one of claims 1-92 for use in a method of treating cancer, said method comprising administering to an individual with cancer an effective amount of the antibody or fusion protein.

106. A method of treating infection comprising administering to an individual in need thereof an effective amount of the antibody or fusion protein according to any one of claims 1-92 or the composition of claim 99.

107. The method of claim 106, wherein the infection is a viral infection.

108. Use of the antibody or fusion protein according to any one of claims 1-92 for the manufacture of a medicament for treating cancer or chronic infection.

109. A method of expanding T cells ex vivo comprising contacting one or more T cells ex vivo with an effective amount of the antibody or fusion protein according to any one of claims 1-92 or the composition of claim 99.

110. The method of claim 109, wherein the one or more T cells are tumor infiltrating lymphocytes (TILs).

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