Anti-BDCA-2 specific antibody and use thereof

Abstract

An anti-BDCA-2 antibody or an antigen-binding fragment thereof. Also provided are a composition comprising the anti-BDCA-2 antibody or the antigen-binding fragment thereof, a nucleic acid encoding the anti-BDCA-2 antibody or the antigen-binding fragment thereof, a vector comprising the nucleic acid, and a host cell. Also provided are a therapeutic use of the anti-BDCA-2 antibody or the antigen-binding fragment thereof and a pharmaceutical composition comprising same.

Description

Anti-BDCA-2 specific antibodies and uses thereof Technical Field

[0001] The present invention relates to an anti-BDCA-2 antibody or antigen-binding fragment thereof. The present invention also relates to compositions comprising the anti-BDCA-2 antibody or antigen-binding fragment thereof, nucleic acids encoding the anti-BDCA-2 antibody or antigen-binding fragment thereof, vectors comprising the nucleic acids, and host cells. The present invention further relates to therapeutic uses of the anti-BDCA-2 antibody or antigen-binding fragment thereof and pharmaceutical compositions comprising the same. Background Art

[0002] Plasmacytoid dendritic cells (pDCs) are a unique subset of dendritic cells. After differentiation from the bone marrow, they enter the bloodstream, with some residing in the T zone and near the B zone of secondary lymphoid organs. In cases of viral infection, pDCs flow into secondary lymphoid organs in large numbers, residing in the T zone and B zone (PMID: 18787223, Blood. 2008 Dec 1; 112(12): 4598-608), and are able to rapidly secrete large amounts of type I interferon (IFN) to respond to viral infection. pDCs primarily rely on intracellular toll-like receptors (TLRs) 7, 8, and 9 to sense invading viruses and bacteria. Activation of these receptors can trigger cytokine production. The body's nucleic acids and invading foreign pathogens are structurally similar, and TLRs recognize self-nucleic acid antigens and activate pDCs. pDCs appear to be involved in the pathogenesis of autoimmune diseases and tumor entities. Studies have shown that infiltrating pDCs in breast and ovarian cancers are associated with poor clinical outcomes, suggesting that pDCs are also involved in the progression of these cancers. pDCs are also directly involved in the progression of multiple myeloma (MM).

[0003] Type I interferon in the body is mainly induced by pDCs when they are stimulated by external factors such as viral infection, dsDNA, ssRNA, etc. (PMID: 15987599, Cell Res. 2005 Jun; 15(6): 407-22). pDCs and the interferon they produce are closely related to the pathology of autoimmune diseases such as systemic lupus erythematosus (SLE), scleroderma, polymyositis, dermatomyositis, psoriasis, Sjoegren syndrome, rheumatoid arthritis, Graves' disease and Hashimoto's disease (PMID: 32489664, Clin Transl Immunology. 2020 May 26; 9(5): e1139). A large number of pDCs can be deposited in the skin of patients with psoriasis and SLE, causing the activation of myxovirus resistance protein 1 (MxA) and other proteins, thereby causing symptoms (PMID: 26837058, Exp Dermatol. 2016 Jun; 25(6): 415-21). Autologous nucleic acid antigens in SLE patients can activate TLRs in pDCs, leading to the production of type I interferon and other cytokines (PMID: 17979852, Immunol Rev. 2007 Dec; 220: 251-69). The type I interferon receptor antagonist saphnero (anifrolumab) has been approved by the FDA for the treatment of SLE (PMID: 32237942, Immunotherapy. 2020 Apr; 12(5): 275-286).

[0004] Blood Dendritic Cell Antigen 2 (BDCA-2, also known as CD303 and CLEC4C) is a pattern recognition receptor (PRR) specifically expressed on the surface of plasmacytoid dendritic cells. It belongs to the type 2 lectin receptor and can recognize certain sugar-containing or glycosylated proteins (PMID: 25995448, J Biol Chem. 2015 Jul 3; 290(27): 16759-71). Known BDCA-2-specific antibodies, such as 24F4A (BIIB059), bind to BDCA2 and induce its internalization, thereby inhibiting the production of type I interferon and co-stimulatory molecules. They can also utilize the Fc end of the antibody to exert ADCC and CDC effects to kill pDCs (PMID: 25762615, EMBO Mol Med. 2015 Apr; 7(4): 464-76; PMID: 20673884, Cell Immunol. 2010; 265(1): 15-22; US9902775B2). BDCA-2-specific antibodies can reduce pDC levels and inhibit downstream signaling of type I interferon in cynomolgus monkeys. In early clinical studies, they can improve the clinical symptoms of SLE patients (PMID: 30645203, J Clin Invest. 2019 Mar 1; 129(3): 1359-1371).

[0005] However, in the field of SLE treatment, there is still an urgent need for new antibodies that specifically recognize BDCA-2 to optimize the treatment of SLE patients, alleviate their symptoms, and improve the clinical efficacy of SLE. This application meets this need.

[0006] SUMMARY OF THE INVENTION

[0007] In a first aspect, the present invention provides an antibody or antigen-binding fragment thereof targeting BDCA-2, which has the following advantages:

[0008] (1) High affinity binding to human BDCA-2 and target cells expressing human BDCA-2;

[0009] (2) High affinity binding to cynomolgus monkey BDCA-2;

[0010] (3) can induce BDCA2 endocytosis;

[0011] (4) It can inhibit the secretion of type I interferon by pDC cells induced by CpG and immune complexes;

[0012] (5) Ability to induce strong ADCC effect;

[0013] (6) Sustained inhibition of BDCA2 expression in cynomolgus monkeys.

[0014] The present invention provides murine anti-BDCA-2 antibodies, chimeric antibodies, and humanized anti-BDCA-2 antibodies that specifically bind to BDCA-2. The anti-BDCA-2 antibodies of the present invention are expected to have minimal immunogenicity in human subjects and be well tolerated by human subjects.

[0015] In one embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising:

[0016] 1) the three heavy chain CDRs (HCDR1, HCDR2, HCDR3) comprised in the heavy chain variable region as shown in SEQ ID NO: 7 and / or the three light chain CDRs (LCDR1, LCDR2, LCDR3) comprised in the light chain variable region as shown in SEQ ID NO: 8;

[0017] 2) the three heavy chain CDRs (HCDR1, HCDR2, HCDR3) contained in the heavy chain variable region as shown in SEQ ID NO: 17 and / or the three light chain CDRs (LCDR1, LCDR2, LCDR3) contained in the light chain variable region as shown in SEQ ID NO: 18.

[0018] In one embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising:

[0019] 1) comprising heavy chain variable region CDRs (HCDR1, HCDR2, HCDR3) and / or light chain variable region CDRs (LCDR1, LCDR2, LCDR3), wherein HCDR1 comprises the sequence as shown in SEQ ID NO: 1, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 1, or consists of SEQ ID NO: 1; HCDR2 comprises the sequence as shown in SEQ ID NO: 2, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 2, or consists of SEQ ID NO: 2; HCDR3 comprises the sequence as shown in SEQ ID NO: 3, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 3, or consists of SEQ ID NO: 3; LCDR1 comprises the sequence as shown in SEQ ID NO: 4, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 4, or consists of SEQ ID NO: NO:4; LCDR2 comprises the sequence shown in SEQ ID NO:5, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:5, or consists of SEQ ID NO:5; LCDR3 comprises the sequence shown in SEQ ID NO:6, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:6, or consists of SEQ ID NO:6; and / or

[0020] 2) comprising heavy chain variable region CDRs (HCDR1, HCDR2, HCDR3) and / or light chain variable region CDRs (LCDR1, LCDR2, LCDR3), wherein HCDR1 comprises the sequence as shown in SEQ ID NO: 11, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO: 11, or consists of SEQ ID NO: 11; HCDR2 comprises the sequence as shown in SEQ ID NO: 12, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO: 12, or consists of SEQ ID NO: 12; HCDR3 comprises the sequence as shown in SEQ ID NO: 13, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO: 13, or consists of SEQ ID NO: 13; LCDR1 comprises the sequence as shown in SEQ ID NO: 14, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO: 14; NO:14 comprises a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, or consists of SEQ ID NO:14; LCDR2 comprises a sequence as shown in SEQ ID NO:15, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO:15, or consists of SEQ ID NO:15; LCDR3 comprises a sequence as shown in SEQ ID NO:16, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO:16, or consists of SEQ ID NO:16.

[0021] In one embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising a heavy chain variable region, wherein:

[0022] 1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 7, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 7, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 7, or consists of SEQ ID NO: 7;

[0023] 2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 17, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 17, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 17, or consists of SEQ ID NO: 17;

[0024] 3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 19, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 19, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 19, or consists of SEQ ID NO: 19;

[0025] 4) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 20, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 20, or consists of SEQ ID NO: 20;

[0026] 5) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 21, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 21, or consists of SEQ ID NO: 21;

[0027] 6) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 26, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 26, or consists of SEQ ID NO: 26;

[0028] 7) the heavy chain variable region comprises, or consists of, the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 27;

[0029] 8) the heavy chain variable region comprises, or consists of, the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 28; or

[0030] 9) The heavy chain variable region comprises the amino acid sequence as shown in SEQ ID NO: 29, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 29, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 29, or consists of SEQ ID NO: 29.

[0031] In one embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising a light chain variable region, wherein:

[0032] 1) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 8, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 8, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 8, or consists of SEQ ID NO: 8;

[0033] 2) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 18, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 18, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 18, or consists of SEQ ID NO: 18;

[0034] 3) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 22, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 22, or consists of SEQ ID NO: 22;

[0035] 4) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 23, or consists of SEQ ID NO: 23;

[0036] 5) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 24, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 24, or consists of SEQ ID NO: 24;

[0037] 6) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 25, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 25, or consists of SEQ ID NO: 25;

[0038] 7) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 30, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 30, or consists of SEQ ID NO: 30;

[0039] 8) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 31, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 31, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 31, or consists of SEQ ID NO: 31; or

[0040] 9) The light chain variable region comprises the amino acid sequence of SEQ ID NO: 32, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 32, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 32, or consists of SEQ ID NO: 32.

[0041] In another embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising a heavy chain variable region and / or a light chain variable region, wherein:

[0042] 1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:7, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:7, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:7, or consists of SEQ ID NO:7; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:8, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:8, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:8, or consists of SEQ ID NO:8;

[0043] 2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 17, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 17, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17, or consists of SEQ ID NO: 17; and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 18, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 18, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 18, or consists of SEQ ID NO: 18;

[0044] 3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:19, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:19, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:19, or consists of SEQ ID NO:19; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:22, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:22, or consists of SEQ ID NO:22;

[0045] 4) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:19, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:19, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:19, or consists of SEQ ID NO:19; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:23, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:23, or consists of SEQ ID NO:23;

[0046] 5) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:19, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:19, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:19, or consists of SEQ ID NO:19, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:24, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:24, or consists of SEQ ID NO:24;

[0047] 6) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:19, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:19, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:19, or consists of SEQ ID NO:19; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:25, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:25, or consists of SEQ ID NO:25;

[0048] 7) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:20, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:20, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:20, or consists of SEQ ID NO:20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:22, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:22, or consists of SEQ ID NO:22;

[0049] 8) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:20, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:20, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:20, or consists of SEQ ID NO:20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:23, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:23, or consists of SEQ ID NO:23;

[0050] 9) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:20, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:20, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:20, or consists of SEQ ID NO:20; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:24, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:24, or consists of SEQ ID NO:24;

[0051] 10) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:20, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:20, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:20, or consists of SEQ ID NO:20; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:25, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:25, or consists of SEQ ID NO:25;

[0052] 11) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:21, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:21, or consists of SEQ ID NO:21; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:22, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:22, or consists of SEQ ID NO:22;

[0053] 12) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:21, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:21, or consists of SEQ ID NO:21; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:23, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:23, or consists of SEQ ID NO:23;

[0054] 13) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:21, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:21, or consists of SEQ ID NO:21, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:24, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:24, or consists of SEQ ID NO:24;

[0055] 14) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:21, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:21, or consists of SEQ ID NO:21, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:25, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:25, or consists of SEQ ID NO:25;

[0056] 15) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:26, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:26, or consists of SEQ ID NO:26, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:30, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:30, or consists of SEQ ID NO:30;

[0057] 16) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:26, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:26, or consists of SEQ ID NO:26; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:31, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:31, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:31, or consists of SEQ ID NO:31;

[0058] 17) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:26, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:26, or consists of SEQ ID NO:26; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:32, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:32, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:32, or consists of SEQ ID NO:32;

[0059] 18) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:27, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:27, or consists of SEQ ID NO:27; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:30, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:30, or consists of SEQ ID NO:30;

[0060] 19) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:27, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:27, or consists of SEQ ID NO:27; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:31, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:31, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:31, or consists of SEQ ID NO:31;

[0061] 20) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:27, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:27, or consists of SEQ ID NO:27; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:32, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:32, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:32, or consists of SEQ ID NO:32;

[0062] 21) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:28, or consists of SEQ ID NO:28; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:30, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:30, or consists of SEQ ID NO:30;

[0063] 22) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:28, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:28, or consists of SEQ ID NO:28; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:31, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:31, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:31, or consists of SEQ ID NO:31;

[0064] 23) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:28, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:28, or consists of SEQ ID NO:28; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:32, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:32, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:32, or consists of SEQ ID NO:32;

[0065] 24) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:29, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:29, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:29, or consists of SEQ ID NO:29; and the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:30, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:30, or consists of SEQ ID NO:30;

[0066] 25) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:29, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:29, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:29, or consists of SEQ ID NO:29, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:31, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:31, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:31, or consists of SEQ ID NO:31; or

[0067] 26) The heavy chain variable region comprises the amino acid sequence of SEQ ID NO:29, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:29, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:29, or consists of SEQ ID NO:29, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:32, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:32, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:32, or consists of SEQ ID NO:32.

[0068] In a specific embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising a heavy chain variable region and / or a light chain variable region, wherein:

[0069] 1) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 7, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 8;

[0070] 2) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 17, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 18;

[0071] 3) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 22;

[0072] 4) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 23;

[0073] 5) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 24;

[0074] 6) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 25;

[0075] 7) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 22;

[0076] 8) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 23;

[0077] 9) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 24;

[0078] 10) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 25;

[0079] 11) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 22;

[0080] 12) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 23;

[0081] 13) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 24;

[0082] 14) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 25;

[0083] 15) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 30;

[0084] 16) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 31;

[0085] 17) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 32;

[0086] 18) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 30;

[0087] 19) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 31;

[0088] 20) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 32;

[0089] 21) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 30;

[0090] 22) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 31;

[0091] 23) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 32;

[0092] 24) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 30;

[0093] 25) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 31; or

[0094] 26) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 32.

[0095] In some embodiments, the above-mentioned antibodies or antigen-binding fragments thereof further comprise heavy chain and / or light chain constant region sequences derived from human antibody germline consensus sequences. In some embodiments, the heavy chain constant region is preferably derived from the constant region sequences of human IgG1, IgG2, IgG3, or IgG4. In another embodiment, the heavy chain constant region comprises or consists of the sequence shown in SEQ ID NO: 9. In one embodiment, the light chain constant region comprises or consists of the sequence shown in SEQ ID NO: 10.

[0096] It will be appreciated that sequence variants of these constant region domains may also be used, for example comprising one or more amino acid modifications, wherein amino acid positions are identified according to the EU index system of Kabat et al. (1991).

[0097] In a specific embodiment, the present invention provides an anti-BDCA-2 antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising a heavy chain and / or a light chain, wherein:

[0098] 1) the heavy chain comprises the amino acid sequence of SEQ ID NO:33, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:33, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:33, or consists of SEQ ID NO:33, and the light chain comprises the amino acid sequence of SEQ ID NO:34, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:34, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:34, or consists of SEQ ID NO:34;

[0099] 2) the heavy chain comprises the amino acid sequence of SEQ ID NO:35, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:35, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:35, or consists of SEQ ID NO:35, and the light chain comprises the amino acid sequence of SEQ ID NO:36, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:36, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:36, or consists of SEQ ID NO:36;

[0100] 3) the heavy chain comprises the amino acid sequence of SEQ ID NO:37, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37, and the light chain comprises the amino acid sequence of SEQ ID NO:38, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38;

[0101] 4) the heavy chain comprises the amino acid sequence of SEQ ID NO:37, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37, and the light chain comprises the amino acid sequence of SEQ ID NO:39, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39;

[0102] 5) the heavy chain comprises, or consists of, the amino acid sequence of SEQ ID NO:37, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:37, and the light chain comprises, or consists of, the amino acid sequence of SEQ ID NO:40, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:40;

[0103] 6) the heavy chain comprises, or consists of, the amino acid sequence of SEQ ID NO:37, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:37, and the light chain comprises, or consists of, the amino acid sequence of SEQ ID NO:41, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:41;

[0104] 7) the heavy chain comprises the amino acid sequence of SEQ ID NO:42, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence of SEQ ID NO:38, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38;

[0105] 8) the heavy chain comprises the amino acid sequence of SEQ ID NO:42, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence of SEQ ID NO:39, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39;

[0106] 9) the heavy chain comprises the amino acid sequence of SEQ ID NO:42, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence of SEQ ID NO:40, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:40, or consists of SEQ ID NO:40;

[0107] 10) the heavy chain comprises the amino acid sequence of SEQ ID NO:42, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence of SEQ ID NO:41, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41;

[0108] 11) the heavy chain comprises the amino acid sequence of SEQ ID NO:43, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence of SEQ ID NO:38, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38;

[0109] 12) the heavy chain comprises the amino acid sequence of SEQ ID NO:43, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence of SEQ ID NO:39, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39;

[0110] 13) the heavy chain comprises the amino acid sequence of SEQ ID NO:43, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence of SEQ ID NO:40, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:40, or consists of SEQ ID NO:40;

[0111] 14) the heavy chain comprises the amino acid sequence of SEQ ID NO:43, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence of SEQ ID NO:41, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41;

[0112] In certain embodiments of the antibody of any of the foregoing, the antibody is monoclonal. In a preferred embodiment, the antibody is a chimeric antibody, and in another more preferred embodiment, the antibody is a humanized antibody.

[0113] In certain embodiments of the antibody of any of the foregoing, the antibody is a full-length antibody.

[0114] In one embodiment, the anti-BDCA-2 antibodies of the present invention are intact antibodies, such as IgG1, IgG2, IgG3, or IgG4 antibodies. In another embodiment, the anti-BDCA-2 antibodies of the present invention encompass only the antigen-binding portion thereof, such as Fab, Fab'-SH, Fv, scFv, or (Fab')2 fragments.

[0115] In a second aspect, the present invention provides an isolated polynucleotide molecule encoding any one of the antibodies or antigen-binding fragments thereof described in the first aspect.

[0116] In a third aspect, the present invention provides a vector comprising the nucleic acid molecule of the third aspect. In one embodiment, the vector is an expression vector.

[0117] In a fourth aspect, the present invention provides a host cell comprising the vector of the fourth aspect or the nucleic acid molecule of the third invention. In some embodiments, the host cell is prokaryotic, such as Escherichia coli. In other embodiments, the host cell is eukaryotic, such as 293 cells, CHO cells, yeast cells, or plant cells.

[0118] In a fifth aspect, the present invention provides a conjugate comprising the antibody or antigen-binding fragment thereof of the present invention and a coupling portion, wherein the coupling portion is another molecule; preferably, the coupling portion is a radioactive isotope, a fluorescent substance, a luminescent substance, a colored substance or an enzyme, etc.

[0119] In a sixth aspect, the present invention provides a pharmaceutical composition comprising the antibody or antigen-binding fragment thereof or the polynucleotide molecule, vector, host cell, conjugate and pharmaceutically acceptable carrier described in the present invention.

[0120] In a seventh aspect, the present invention provides a method for preparing the anti-BDCA-2 antibody or antigen-binding fragment thereof described herein, the method comprising expressing the antibody or antigen-binding fragment thereof in a host cell described herein under conditions suitable for expression of the antibody or antigen-binding fragment thereof, and recovering the expressed antibody or antigen-binding fragment thereof from the host cell.

[0121] In an eighth aspect, the present invention provides a method for treating a disease in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of an antibody or antigen-binding fragment thereof of the present invention or a polynucleotide molecule, vector, host cell, conjugate of the present invention or a therapeutically effective amount of a pharmaceutical composition of the present invention.

[0122] In one embodiment, the disease is an autoimmune disease or cancer, such as systemic lupus erythematosus (SLE), scleroderma, polymyositis, dermatomyositis, psoriasis, Sjoegren's syndrome, rheumatoid arthritis, Graves' disease and Hashimoto's disease; breast tumors, ovarian cancer, multiple myeloma (MM), etc.

[0123] In a ninth aspect, the present invention provides a method for preventing and / or treating tumors or autoimmune diseases in a subject, the method comprising administering to a subject in need thereof an effective amount of the antibody or antigen-binding fragment thereof described in the present invention or the polynucleotide molecule, vector, host cell, conjugate or pharmaceutical composition of the present invention, etc.

[0124] In one embodiment, the present invention provides an antibody or antigen-binding fragment thereof disclosed herein or a polynucleotide molecule, vector, host cell, conjugate or pharmaceutical composition of the present invention for use as a medicament.

[0125] In one embodiment, the present invention provides an antibody or antigen-binding fragment thereof disclosed herein or a polynucleotide molecule, vector, host cell, conjugate or pharmaceutical composition of the present invention for use in therapy.

[0126] In a specific embodiment, the present invention provides a method for reducing or eliminating circulating pDC cells, comprising administering to the subject an effective amount of the antibody or antigen-binding fragment thereof of the present invention, or the polynucleotide molecule, vector, host cell, conjugate of the present invention, or an effective amount of the pharmaceutical composition of the present invention.

[0127] In a tenth aspect, the present invention provides use of an anti-BDCA-2 antibody or antigen-binding fragment thereof, or a polynucleotide molecule, vector, host cell, conjugate, or pharmaceutical composition of the present invention in the preparation of a medicament for treating an autoimmune disease or cancer.

[0128] In one embodiment, any of the antibodies or antigen-binding fragments thereof described in the first aspect is used to treat an autoimmune disease or cancer. In one embodiment, the autoimmune disease or cancer is, for example, systemic lupus erythematosus (SLE), scleroderma, polymyositis, dermatomyositis, psoriasis, Sjoegren's syndrome, rheumatoid arthritis, Graves' disease, Hashimoto's disease, or other autoimmune diseases; breast tumors, ovarian cancer, multiple myeloma (MM), etc.

[0129] In an eleventh aspect, the present invention provides a kit comprising the antibody or antigen-binding fragment or conjugate thereof of the present invention.

[0130] In an eleventh aspect, the present invention provides a method for detecting the presence or level of BDCA-2 in a sample, comprising contacting the sample with an antibody, antigen-binding fragment, or conjugate thereof of the present invention, and detecting whether the antibody, antigen-binding fragment, or conjugate thereof forms a complex with BDCA-2.

[0131] The present invention is further illustrated in the following drawings and specific embodiments. However, these drawings and specific embodiments should not be considered to limit the scope of the present invention, and changes that are readily apparent to those skilled in the art will be included within the spirit of the present invention and the protection scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0132] Figure 1 shows the binding activity of purified hybridoma supernatants against Jurkat-hBDCA-2 cells, with BIIB059 serving as a control antibody. Figure 1A shows the binding activity of hybridoma 17G6A2 supernatant against Jurkat-hBDCA-2 cells, Figure 1B shows the binding activity of hybridoma 164C11B8 supernatant against Jurkat-hBDCA-2 cells, Figure 1C shows the binding activity of hybridoma 17G6A2 supernatant against Jurkat-cynoBDCA-2 cells, and Figure 1D shows the binding activity of hybridoma supernatant 164C11B8 against Jurkat-cynoBDCA-2 cells.

[0133] Figure 2 shows the inhibitory activity of purified hybridoma supernatants on CpGA-induced type I interferon production in human PBMC cells. Figure 2A shows the activity of hybridoma 17G6A2, and Figure 2B shows the activity of hybridoma 164C11B8. BIIB059 is a control antibody.

[0134] FIG3A shows the binding activity of the chimeric antibody to Jurkat h-BDCA-2 cells, and FIG3B shows the binding activity of the chimeric antibody to Jurkat-cyno-BDCA-2 cells. BIIB059 is a control antibody.

[0135] Figure 4 shows the inhibitory activity of chimeric antibodies on CpGA-induced type I interferon production in human PBMC cells. Figure 4A shows the activity of chimeric antibody 17G6A2_hIgG1, and Figure 4B shows the activity of chimeric antibody 164C11B8_hIgG1. BIIB059 is a control antibody.

[0136] Figure 5 shows the inhibitory activity of chimeric antibodies on immune complex-induced type I interferon production in human pDC cells. Figure 5A shows the activity of chimeric antibody 17G6A2_hIgG1, and Figure 5B shows the activity of chimeric antibody 164C11B8_hIgG1. BIIB059 is a control antibody.

[0137] FIG6 shows the activation activity of the chimeric antibody on Jurkat-human FcγRIIIa(158V)-NFAT cells.

[0138] Figure 7 shows the binding activity of humanized antibodies against Jurkat cells expressing BDCA-2. Figure 7A shows the activity of the humanized antibody 17G6A2 against Jurkat cells expressing human BDCA-2. Figure 7B shows the activity of the humanized antibody 164C11B8 against Jurkat cells expressing human BDCA-2. Figure 7C shows the activity of the humanized antibody 17G6A2 against Jurkat cells expressing cynomolgus monkey BDCA-2. Figure 7D shows the activity of the humanized antibody 164C11B8 against Jurkat cells expressing cynomolgus monkey BDCA-2. Figure 7E shows that neither the humanized antibodies 17G6A2 nor BIIB059 bind to Jurkat null cells.

[0139] Figure 8 shows the inhibitory activity of the humanized antibody 17G6A2 on the production of type I interferon by human PBMC cells induced by CpGA

[0140] FIG9 shows the inhibitory activity of the humanized antibody 17G6A2 on the production of type I interferon by human pDC cells induced by immune complexes.

[0141] FIG10 shows the binding activity of humanized antibodies to human pDC.

[0142] FIG11A shows that anti-BDCA-2 antibodies do not bind to CLEC4A, FIG11B shows that anti-BDCA-2 antibodies do not bind to CLEC4D, FIG11C shows that anti-BDCA-2 antibodies do not bind to CLEC6A, and FIG11D shows that anti-BDCA-2 antibodies do not bind to CLEC4E.

[0143] FIG12 shows the activation activity of humanized antibodies against Jurkat-human FcγRIIIa(158V)-NFAT cells.

[0144] FIG. 13 shows that 17G6A2_hzH1L5_hIgG1 or BIIB059 induces BDCA2 internalization on the surface of pDC cells.

[0145] FIG. 14 shows that 17G6A2_hzH1L5_hIgG1 or BIIB059 binds to BDCA2 on the surface of cynomolgus monkey pDC cells.

[0146] Detailed Description of the Invention

[0147] All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In addition, the materials, methods and examples described herein are illustrative only and are not intended to be limiting. Other features, objects and advantages of the present invention will be apparent from this specification and the accompanying drawings and from the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. For the purposes of the present invention, the following terms are defined below.

[0148] definition

[0149] The term "about" when used in conjunction with a numerical value is meant to encompass the numerical value within a range having a lower limit that is 5% less than the specified numerical value and an upper limit that is 5% greater than the specified numerical value.

[0150] The term "and / or" should be understood to mean any one of the options or a combination of any two or more of the options.

[0151] As used herein, the term "comprises" or "includes" means including the stated elements, integers or steps, but does not exclude any other elements, integers or steps. In this article, when the term "comprises" or "includes" is used, unless otherwise indicated, it also covers the situation consisting of the stated elements, integers or steps.

[0152] The term "antibody" is used herein in the broadest sense to refer to a protein that contains an antigen binding site.

[0153] The term "immunoglobulin" refers to a protein with the structure of a naturally occurring antibody and is generally used interchangeably with the term "antibody" in this application. IgG immunoglobulins are heterotetrameric glycoproteins consisting of two light chains and two heavy chains bonded by disulfide bonds. From the N-terminus to the C-terminus, each immunoglobulin heavy chain has a heavy chain variable region (VH), also known as a heavy chain variable domain, followed by three heavy chain constant domains (CH1, CH2, and CH3). Similarly, from the N-terminus to the C-terminus, each immunoglobulin light chain has a light chain variable region (VL), also known as a light chain variable domain, followed by a light chain constant domain (CL). In IgG molecules, the VH-CH1 of the heavy chain is usually paired with the VL-CL of the light chain to form a Fab fragment that specifically binds to the antigen. Therefore, an IgG immunoglobulin is essentially composed of two Fab molecules connected by the immunoglobulin hinge region and two dimerized Fc regions. The heavy chains of immunoglobulins can be assigned to one of five classes, called α (IgA), δ (IgD), ε (IgE), γ (IgG), or μ (IgM), based on the type of their constant region, some of which can be further divided into subclasses, such as γ1 (IgG1), γ2 (IgG2), γ3 (IgG3), γ4 (IgG4), α1 (IgA1), and α2 (IgA2). The light chains of immunoglobulins can also be assigned to one of two types, called κ and λ, based on the amino acid sequence of their constant domains.

[0154] "Complementarity determining regions" or "CDR regions" or "CDRs" or "hypervariable regions" are regions of an antibody variable domain that are highly variable in sequence and form structurally defined loops ("hypervariable loops") and / or contain antigen-contacting residues ("antigen contact points"). CDRs are primarily responsible for binding to antigenic epitopes.

[0155] A variety of methods are known in the art for determining CDR sequences within a given VH or VL amino acid sequence: Kabat complementarity determining regions (CDRs) are determined based on sequence variability and are the most commonly used (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Edition, Public Health Service, National Institutes of Health, Bethesda, Md. (1991)), while Chothia refers to the positions of structural loops (Chothia et al., (1987) J. Mol. Biol. 196: 901-917; Chothia et al. (1989) Nature 342: 877-883). AbM CDRs are a compromise between Kabat CDRs and Chothia structural loops and are used by Oxford Molecular's AbM antibody modeling software. "Contact" CDRs are based on analysis of available complex crystal structures. The residues for each of these CDRs, according to the different CDR determination methods, are described below.

[0156] When referring to antibodies defined by specific CDR sequences defined herein, the scope of said antibodies also encompasses antibodies whose variable region sequences comprise said specific CDR sequences, but whose declared CDR boundaries differ from the specific CDR boundaries defined herein due to the application of a different scheme (e.g., a different assignment system rule or combination).

[0157] The CDRs of the antibodies of the present invention can be manually assessed to determine their boundaries according to any protocol or combination thereof in the art. Unless otherwise indicated, in the present invention, the term "CDR" or "CDR sequence" encompasses CDR sequences determined in any of the above ways.

[0158] The terms "antigen binding site" and "antigen binding domain" are used interchangeably to refer to the region of an antibody molecule that actually binds to an antigen. Antigen binding sites include, but are not limited to, Fv, Fab fragments, Fab', Fab'-SH, F(ab')2, single-chain antibody molecules (e.g., scFv), VHH, and other formats.

[0159] The term "variable region" or "variable domain" of an antibody refers to the domain of the antibody heavy or light chain that participates in binding of the antibody to the antigen. The variable region of an antibody can be further divided into hypervariable regions (i.e., complementary determining regions (CDRs)) and relatively conserved regions (i.e., framework regions (FRs)) interposed between the hypervariable regions. In the case of IgG immunoglobulins, the heavy chain variable region or light chain variable region comprises FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4, respectively, from N-terminus to C-terminus. In the case of heavy chain antibodies (also referred to herein as nanobodies), for example, heavy chain antibodies from Camelidae, the antigen binding site is composed of a single VH domain (i.e., "VHH" domain). The VHH of a natural heavy chain antibody has a similar structure to the heavy chain variable region of a natural IgG antibody, i.e., comprises four conserved framework regions (FRs) and three complementary determining regions (CDRs).

[0160] "Heavy chain constant region domain" or "heavy chain constant region" refers to a constant region domain from, obtained from, or derived from an immunoglobulin heavy chain, comprising heavy chain constant regions CH1, CH2, CH3, and optionally heavy chain constant region CH4 covalently linked sequentially from N-terminus to C-terminus. In most cases, the heavy chain constant regions CH1 and CH2 are connected by a heavy chain hinge region, but may also be connected by a flexible linker when appropriate.

[0161] The term "EC 50 ”, also known as the “half-maximal effective concentration”, is the concentration of a drug, antibody, or toxic agent that induces a response that is 50% between baseline and maximum after a specified exposure time.

[0162] As used herein, the term "binding" or "specific binding" means that the binding is selective for the antigen and can be distinguished from unwanted or non-specific interactions. The ability of an antigen binding site to bind to a specific antigen can be determined by enzyme-linked immunosorbent assay (ELISA) or conventional binding assays known in the art.

[0163] "Affinity" or "binding affinity" refers to the intrinsic binding ability that reflects the interaction between members of a binding pair. The affinity of a molecule X for its binding partner Y can be expressed by the equilibrium dissociation constant (K D ) indicates that the equilibrium dissociation constant is the dissociation rate constant and the association rate constant (k dis and k on Binding affinity can be measured by common methods known in the art.

[0164] Amino acid mutations can be amino acid substitutions, deletions, insertions, and / or additions. In some embodiments, amino acid mutations are substitutions of one or more amino acids, such as single amino acid substitutions or combinations of multiple amino acid substitutions. Amino acid deletions and insertions include deletions and insertions at the amino and / or carboxyl termini of a polypeptide sequence, as well as deletions and insertions within the polypeptide sequence. Amino acid substitutions of the present invention optionally include conservative amino acid substitutions.

[0165] "Percent (%) identity" of an amino acid sequence refers to the percentage of amino acid residues in the candidate sequence that are identical to the amino acid residues in the specific amino acid sequence set forth in this specification, after aligning the candidate sequence with the specific amino acid sequence set forth in this specification and introducing gaps, if necessary, to achieve the maximum percentage identity, and not considering any conservative substitutions as part of the sequence identity. In some embodiments, the present invention contemplates variants of the antibody molecules of the invention that have a substantial degree of identity, e.g., at least 80%, 85%, 90%, 95%, 97%, 98% or 99% or more, relative to the antibody molecules and sequences thereof specifically disclosed herein. The variants may comprise conservative modifications.

[0166] With respect to polypeptide sequences, "conservative modifications" include substitutions, deletions, or additions to a polypeptide sequence that result in the substitution of an amino acid with a chemically similar amino acid. Conservative substitution tables providing functionally similar amino acids are well known in the art. Such conservatively modified variants are in addition to and do not exclude the polymorphic variants, interspecies homologs, and alleles of the present invention. The following eight groups contain amino acids that are conservative substitutions for each other: 1) Alanine (A), Glycine (G); 2) Aspartic Acid (D), Glutamic Acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W); 7) Serine (S), Threonine (T); and 8) Cysteine ​​(C), Methionine (M) (see, e.g., Creighton, Proteins (1984)). In some embodiments, the term "conservative sequence modifications" is used to refer to amino acid modifications that do not significantly affect or alter the binding characteristics of the antibody containing the amino acid sequence.

[0167] The terms "individual" or "subject" are used interchangeably and refer to mammals. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In particular, the individual is a human.

[0168] The term "treatment" refers to a clinical intervention intended to alter the natural course of a disease in the individual being treated. Desired therapeutic effects include, but are not limited to, preventing the onset or recurrence of the disease, alleviating symptoms, reducing any direct or indirect pathological consequences of the disease, preventing metastasis, reducing the rate of disease progression, ameliorating or palliating the disease state, and alleviating or improving prognosis. In some embodiments, the antibody molecules of the present invention are used to delay the development of the disease or to slow the progression of the disease.

[0169] The term "prevent" includes the inhibition of the development or progression of a disease or condition or symptoms of a particular disease or condition. In some embodiments, subjects with a family history of cancer are candidates for a preventative regimen. Generally, in the context of cancer, the term "prevent" refers to the administration of a drug before the development of signs or symptoms of cancer, particularly in a subject at risk for cancer.

[0170] The term "effective amount" refers to an amount or dosage of an antibody or composition of the present invention that produces the desired effect in a patient in need of treatment or prevention after administration to the patient in a single or multiple doses. The effective amount can be readily determined by the attending physician, who is skilled in the art, by considering a variety of factors such as the species of the mammal; weight, age, and general health; the specific disease involved; the extent or severity of the disease; the response of the individual patient; the specific antibody administered; the mode of administration; the bioavailability characteristics of the administered formulation; the selected dosing regimen; and the use of any concomitant therapy.

[0171] The term "therapeutically effective amount" refers to an amount that is effective to achieve the desired therapeutic outcome at the desired dosage and for the desired period of time. The therapeutically effective amount of an antibody or antibody fragment or composition can vary depending on factors such as the disease state, the age, sex, and weight of the individual, and the ability of the antibody or antibody portion to stimulate the desired response in the individual. A therapeutically effective amount is also an amount in which any toxic or deleterious effects of the antibody or antibody fragment or composition are outweighed by the therapeutically beneficial effects. A "therapeutically effective amount" preferably inhibits a measurable parameter by at least about 20%, more preferably at least about 40%, even more preferably at least about 50%, 60%, or 70%, and still more preferably at least about 80% or 90%, relative to an untreated subject.

[0172] The term "prophylactically effective amount" refers to an amount effective to achieve the desired preventive result at the required dosage and for the required period of time. Typically, a prophylactic effective amount will be less than a therapeutically effective amount because a prophylactic dose is used in a subject prior to or at an earlier stage of disease.

[0173] The term "pharmaceutical composition" refers to a composition that is in form permitting the biological activity of the active ingredient contained therein to be effective, and that contains no additional ingredients that are unacceptably toxic to a subject to which the composition would be administered.

[0174] Polynucleotides, vectors and hosts

[0175] The present invention provides nucleic acids encoding any of the above-mentioned antibody molecules or antigen-binding fragments thereof. Polynucleotide sequences encoding the antibody molecules or antigen-binding fragments thereof of the present invention can be generated by de novo solid-phase DNA synthesis or genetic engineering methods using methods well known in the art. In addition, the polynucleotides and nucleic acids of the present invention may include a segment encoding a secretory signal peptide, which can be operably linked to the segment encoding the antibody molecules or antigen-binding fragments thereof of the present invention, thereby directing the secretory expression of the antibody molecules or antigen-binding fragments thereof of the present invention.

[0176] The present invention also provides vectors comprising nucleic acids of the present invention. In one embodiment, the vector is an expression vector, such as a eukaryotic expression vector and a prokaryotic expression vector. "Expression vector" refers to a vector comprising a recombinant polynucleotide comprising an expression control sequence operatively linked to the nucleotide sequence to be expressed. The expression vector comprises sufficient cis-acting elements for expression; other elements for expression can be provided by the host cell or in an in vitro expression system. Expression vectors include all those known in the art, including cosmids, plasmids (e.g., naked or contained in liposomes) and viruses (e.g., lentiviruses, retroviruses, adenoviruses, and adeno-associated viruses) into which the recombinant polynucleotide is incorporated.

[0177] The present invention also provides prokaryotic and eukaryotic host cells comprising the nucleic acid or the vector. Host cells include "transformants" and "transformed cells", which include primary transformed cells and progeny derived therefrom. Host cells are any type of cell system that can be used to produce the antibody molecules of the present invention, including eukaryotic cells, for example, mammalian cells, insect cells, yeast cells; and prokaryotic cells, for example, Escherichia coli cells. Host cells include cultured cells, and also include cells within transgenic animals, transgenic plants, or cultured plant tissues or animal tissues. Host cells suitable for replicating and supporting the expression of the antibody molecules of the present invention or their antigen-binding fragments are well known in the art. Such cells can be transfected or transduced with specific expression vectors, and large quantities of vector-containing cells can be grown for inoculation of large-scale fermenters to obtain sufficient amounts of antibody molecules.

[0178] Pharmaceutical compositions and pharmaceutical preparations

[0179] The present invention also includes compositions (including pharmaceutical compositions or pharmaceutical preparations) comprising the antibody molecules of the present invention or their antigen-binding fragments and compositions comprising polynucleotides encoding the antibody molecules of the present invention or their antigen-binding fragments. These compositions may also optionally contain suitable pharmaceutical excipients, such as pharmaceutical carriers and pharmaceutical excipients known in the art, including buffers.

[0180] The pharmaceutical composition or preparation of the present invention may also comprise one or more other active ingredients or be used in combination with one or more other active ingredients. The active ingredients are required for the specific indication being treated, preferably having those active ingredients that do not adversely affect the complementary activities of each other. For example, it is desirable to also provide other active ingredients for the treatment of autoimmune diseases, which are suitably combined in an amount effective for the intended use.

[0181] Treatment methods and uses

[0182] As used herein, the terms "individual" or "subject" are used interchangeably to refer to mammals. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In particular, the subject is a human.

[0183] The present invention provides a method for treating an autoimmune disease or cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of an antibody or antigen-binding fragment thereof of the present invention, or a therapeutically effective amount of a pharmaceutical composition of the present invention. In one embodiment, the autoimmune disease or cancer is, for example, systemic lupus erythematosus (SLE), scleroderma, polymyositis, dermatomyositis, psoriasis, Sjoegren's syndrome, rheumatoid arthritis, Graves' disease, Hashimoto's disease, or other autoimmune diseases; breast tumors, ovarian cancer, multiple myeloma (MM), etc.

[0184] In one embodiment, the present invention provides a method for reducing or eliminating circulating pDC cells expressing BDCA-2, comprising administering to the subject an effective amount of the antibody or antigen-binding fragment thereof of the present invention, or an effective amount of the pharmaceutical composition of the present invention.

[0185] The antibody molecule of the present invention or its antigen-binding fragment (and pharmaceutical composition comprising it) can be administered by any suitable method, including parenteral administration, intrapulmonary administration and intranasal administration, and, if local treatment needs, intralesional administration. Parenteral infusion includes intramuscular, intravenous, intraarterial, intraperitoneal or subcutaneous administration. To a certain extent, it is short-term or long-term according to the medication, and can be administered by any suitable route, for example, by injection, such as intravenous or subcutaneous injection. Various medication schedules are contemplated herein, including, but not limited to, single administration or multiple administrations at multiple time points, push administration and pulse infusion.

[0186] For the prevention or treatment of disease, the appropriate dosage of the antibody molecules of the invention or antigen-binding fragments thereof (when used alone or in combination with one or more other therapeutic agents) will depend on the type of disease being treated, the severity and course of the disease, whether administration is for preventive or therapeutic purposes, previous therapy, the patient's clinical history, and the judgment of the attending physician.

[0187] The following examples are described to assist understanding of the present invention. The examples are not intended to, and should not be interpreted in any way as, limiting the scope of protection of the present invention. Example

[0188] The experimental methods described in the following examples, unless otherwise specified, are conventional methods in the art using default parameters and procedures. The experimental materials used, unless otherwise specified, are all commercially available products. Where specific techniques or conditions are not specified in the examples, the experiments were performed according to those described in the literature in the art or in accordance with the instructions of the corresponding products. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased through regular channels.

[0189] Example 1: Mouse hybridoma producing anti-human BDCA-2

[0190] In this example, mice were immunized using two methods to obtain anti-human BDCA-2 antibodies. Specifically, mice were immunized using mRNA encoding full-length human BDCA-2 (UniProtKB:Q8WTT0) (prepared by Shanghai Hongcheng Pharmaceutical Co., Ltd.) and an extracellular fragment of the human BDCA-2 (UniProtKB:Q8WTT0) protein as immunogens. The specific methods are as follows:

[0191] 1. Animal immunization

[0192] A. The extracellular fragment of the human BDCA-2 protein was used as the immunogen, mixed with Freund's adjuvant (SIGMA, Cat. Nos. F5506 and F5881) at a 1:1 ratio. Six- to eight-week-old Balb / c female and SJL female mice were then immunized with the protein according to standard methods. After the first immunization with 50 μg / mouse, a second immunization with 25 μg / mouse was performed two weeks later, followed by a third immunization with 25 μg / mouse after another two weeks. Ten days after the final immunization, a booster immunization with the protein fragment was performed. Three days later, the spleens of the mice were harvested for cell fusion.

[0193] B. mRNA encoding full-length human BDCA-2 was used as an immunogen (50 μg / mouse) and packaged into lipid nanoparticles (LNPs). Balb / c female mice and SJL female mice were then immunized with mRNA according to conventional methods. Immunizations were repeated three or four times at three-week intervals. A booster immunization with the protein was performed seven days after the final immunization. Three days later, spleens were harvested from the mice for cell fusion.

[0194] 2. Cell Fusion

[0195] Mouse spleen cells and SP2 / 0 cells (ATCC No. CRL-1581) were electrofused at a ratio of 2:1 (BTX electrofusion instrument: ECM2001 + ), cultured in 96-well culture plates with HAT medium (GIBCO, catalog number: H0262), and hybridoma cell supernatant antibody screening was performed after 10 days.

[0196] 3. Positive clone screening

[0197] Cells expressing human BDCA-2 (Jurkat-hBDCA-2, constructed by Jiman Biotech (Shanghai) Co., Ltd.) and cynomolgus monkey BDCA-2 (Jurkat-cynoBDCA-2, constructed by Jiman Biotech (Shanghai) Co., Ltd.) were cultured at 2×10 6 / mL density, 50 μL / well were plated in a 96-well U-shaped assay plate. 50 μL of hybridoma cell culture supernatant was added and incubated at 4°C for 1 hour. Cells were washed twice with FACS buffer (PBS solution containing 1% FBS) by centrifugation at 300g. A 1:1000 dilution of AlexaFlour-647-conjugated anti-mouse secondary antibody (Invitrogen, Catalog No. A21445) was added and incubated for 30 minutes. Cells were washed three times with FACS buffer by centrifugation at 300g. The mean fluorescence intensity (MFI) of each well was measured using a flow cytometer (BECKMAN COULTER cytoFLEX). Wells with higher mean fluorescence intensity (MFI) for human BDCA-2 and cynomolgus monkey BDCA-2 binding than the isotype control indicate that the antibodies secreted by the corresponding clones bind to human and cynomolgus monkey BDCA-2 proteins. Cells from the wells containing positive clones were mixed and pipetted into a centrifuge tube. An appropriate amount of culture medium was added, and a small amount of cells were aspirated and counted. Based on the count results, the hybridoma cells were diluted to 5 cells per mL. 0.2 mL of the cell suspension was added to each well of a 96-well plate. After one week of culture, the culture supernatant containing single cell colonies was selected and tested again using the above method. The corresponding clones are shown in Table 1.

[0198] Table 1 Positive hybridoma clones binding to human BDCA-2 and cynomolgus monkey BDCA-2

[0199] Example 2: Preparation, purification and functional characterization of mouse monoclonal antibodies against human BDCA-2

[0200] Hybridoma cells with binding activity to human and cynomolgus macaque BDCA-2 listed in Table 1 were cultured in serum-free medium according to conventional methods. After 10 days, the culture supernatant was collected and purified using a Protein A column (Bioglone (Shanghai) Biotechnology Co., Ltd., Catalog No. AA0272) to obtain purified monoclonal antibodies (named after the hybridoma). The purified anti-human BDCA-2 antibodies were then tested for activity and function.

[0201] 2.1 Detection of Binding Activity of Hybridoma Monoclonal Antibodies Against Human BDCA-2

[0202] The density is 1×10 6Jurkat-hBDCA-2 cells expressing human BDCA-2 or Jurkat-cynoBDCA-2 cells expressing cynomolgus monkey BDCA-2 were plated in a 96-well U-bottom plate at a concentration of 100 μL per well, and the cells were pelleted by centrifugation. The anti-BDCA-2 hybridoma antibodies (17G6A2 and 164C11B8) obtained in Example 1 and the positive control antibody BIIB059 (patent US9902775B2, which has the light chain shown in SEQ ID NO: 3 and the heavy chain shown in SEQ ID NO: 4 disclosed in US9902775B2) were first diluted with FACS buffer to a starting working mass concentration of 10 μg / mL, and then diluted in a 1:3 doubling gradient with FACS buffer to prepare 10 dilution samples. The negative control antibody IgG1 isotype (Baiying Biotechnology Co., Ltd., catalog number: B117901) was diluted to a starting working mass concentration of 10 μg / mL. Then, 100 μL of each dilution of the antibody was added to the corresponding wells of a 96-well plate. The cell pellet was resuspended and mixed, incubated at 4°C for 1 hour, centrifuged to remove the supernatant, and the cells were washed three times with FACS buffer. Alexa Flour-647-labeled anti-mouse secondary antibody (Invitrogen, Catalog No. A21445) was diluted 1:1000 and added to each well with 100 μL of secondary antibody dilution. The cell pellet was resuspended and incubated at 4°C for 1 hour. The supernatant was removed by centrifugation, and the cells were washed three times and resuspended in 100 μL of FACS buffer per well. The mean fluorescence intensity (MFI) was analyzed by flow cytometry. Graphpad Prism 8.0 software was used to analyze the experimental data. The logarithm of the anti-BDCA-2 monoclonal antibody concentration was plotted on the x-axis and the corresponding MFI value on the y-axis. A four-parameter regression model was used to fit the anti-BDCA-2 monoclonal antibody dose-effect curve and calculate the EC value. 50 , the obtained EC 50 is the average of multiple repeated experiments.

[0203] The results are shown in Figures 1A, 1B, 1C, and 1D and Table 2. EC values ​​for the binding activity of 17G6A2 and 164C11B8 hybridoma supernatants to human BDCA-2 50 The EC values ​​for BDCA-2 binding activity were 96.8 and 189.1 ng / mL, respectively. 50 The EC values ​​of BIIB059 for binding to human and cynomolgus monkey BDCA-2 were 107.4 and 233.0 ng / mL, respectively. 50 224.2 and 207.3 ng / mL respectively.

[0204] Table 2 Binding activity of anti-BDCA-2 antibodies to human BDCA-2 and cynomolgus monkey BDCA-2

[0205] 2.2 Hybridoma monoclonal antibodies against human BDCA-2 inhibit IFNα production by PBMC

[0206] The short single-stranded DNA fragment CpGA stimulates pDCs to produce a strong type I interferon. Activated BDCA-2 can inhibit the production of type I interferon by pDCs induced by CpGA. Anti-BDCA-2 antibodies bind to BDCA-2 and activate downstream BCR signaling, inhibiting the production of type I interferon by pDCs induced by CpGA (PMID: 25762615, EMBO Mol Med. 2015 Apr; 7(4): 464-76). In this section, CpGA was used to induce IFNα production in PBMCs, and the inhibitory effect of anti-BDCA-2 hybridoma antibodies on the produced type I interferon was tested.

[0207] The specific method is as follows: dilute PBMC to 2×10 7 Cells / mL were plated at 50 μL per well in a 96-well U-shaped plate. Anti-BDCA-2 hybridoma antibody and positive control antibody BIIB059 were diluted to 20 μg / mL in RMPI1640 complete medium and then serially diluted 1:4 in RMPI1640 complete medium to create 10 dilutions. The negative control antibody, IgG1 isotype, was diluted to 20 μg / mL. Then, 50 μL of each dilution of antibody was added to the corresponding wells of the 96-well plate. 1 μL of 100 μM CpGA (Invivogen, Catalog No. tlrl-2216) was added to each well and the plate was incubated at 37°C with 5% CO2 for 16 hours. 16 μL of supernatant from each well was aspirated and added to the corresponding wells of a 384-well plate. The IFNα concentration in the supernatant was determined using the Human IFN alpha kit (cisbio, Catalog No. 62HIFNAPEG) according to the manufacturer's instructions. Specifically, 4 μL of IFNαd2 and 4 μL of crypate antibody mixture were added and incubated at room temperature for 2 hours. Relative light units (RLU) were read on the cell culture plate using a microplate reader. Graphpad Prism 8.0 software was used to analyze the data. A four-parameter regression model was used to fit the dose-response curve for anti-BDCA-2 mAb, with the logarithm of the anti-BDCA-2 mAb concentration plotted on the x-axis and the corresponding RLU values ​​plotted on the y-axis.

[0208] The results are shown in Figures 2A, 2B and Table 3. Purified 17G6A2 and 164C11B8 hybridoma antibodies inhibited the EC production of type I interferon induced by CpGA in PBMC. 50BIIB059 inhibits the EC of CpGA-induced PBMC to produce type I interferon. 50 The concentrations of PBMCs in Tables 3.1 and 3.2 were 13.2 and 2.0 ng / mL, respectively. The PBMCs used in Tables 3.1 and 3.2 were from different donors.

[0209] Table 3.1 Inhibitory activity of anti-BDCA-2 antibodies on CpGA-induced type I interferon production in human PBMC cells

[0210] Table 3.2 Inhibitory activity of anti-BDCA-2 antibodies on CpGA-induced type I interferon in human PBMC cells

[0211] Example 3. Construction, expression and purification of chimeric anti-BDCA-2 antibodies

[0212] Antibodies 17G6A2 and 164C11B8, produced by hybridoma clones 17G6A2 and 164C11B8, were sequenced to obtain the variable region sequences of the corresponding antibodies, as shown in Table 4.1. Conventional methods were used to construct the light and heavy chain variable regions of hybridoma antibodies 17G6A2 and 164C11B8 onto human constant regions (IgG1 / κ, Table 4.2), respectively, to obtain chimeric antibodies designated 17G6A2-hIgG1 and 164C11B8-hIgG1. Sequencing confirmed that the constructed hIgG1 chimeric antibodies were consistent with the sequences in Tables 4.1 and 4.2. The corresponding nucleic acids encoding the chimeric antibodies 17G6A2-hIgG1 and 164C11B8-hIgG1 were transfected into Expi293 cells for antibody expression and purification using a Protein A column as follows:

[0213] Expi293 cells expressing antibodies: One day before transfection, dilute the Expi293 cells to a density of 1.5 × 10 6 cells / mL, and cultured in a shaker at 120 rpm at 37°C and 8% CO2. The next day, the viable cell density and survival rate were determined. The cell transfection density should be 3×10 6cells / mL, with a cell viability greater than 95%. Prepare the PEI / plasmid complex: Mix PEI (1 mg / mL, Polysciences, Catalog No. 24765-1) by inverting. Dilute the plasmid containing the encoding nucleic acid in OPM-293 CD05 Medium (OPM, Catalog No. 81075-001) to a total of 1 μg / mL. The volume of medium used to dilute the plasmid should be 1 / 20 of the transfection volume. Mix gently, and the light chain to heavy chain ratio should be 1:1.5. Dilute the PEI reagent in OPM-293 CD05 Medium to a volume of medium used to dilute the PEI to 1 / 20 of the transfection volume. Mix gently by inverting, and incubate at room temperature for 5 minutes. Add the diluted PEI reagent to the diluted plasmid and mix gently by inverting. Incubate the PEI / plasmid complex at room temperature for 15 minutes, then slowly add the solution dropwise to the transfer shaker, gently swirling the shaker during addition. After transfection, incubate the flask in a shaker at 37°C, 8% CO2, and 120 rpm. On the second day after transfection (24 hours after transfection), add 10% OPM-293 ProFeed (OPM, Catalog No. F081918) to the flask. Gently swirl the flask during addition. Return the flask to the shaker and continue incubation for 5-7 days. Harvest the supernatant.

[0214] Protein A column for antibody purification: Prepare a gravity chromatography column. Open the column cap, place the gasket at the bottom of the column, and tighten. Prepare Protein A (Cytiva, Cat. No. 17549801). Accurately calculate the required filler suspension volume based on the target filler volume and filler suspension ratio: Required filler suspension volume = target filler volume / filler suspension ratio. Vortex the filler thoroughly to ensure complete suspension. Add the filler suspension to the bottom of the gravity chromatography column. Add at least 10 CV of equilibration buffer (PBS) to the column. After equilibration, check the pH at the outlet. If the target pH has not been reached, continue adding equilibration buffer until it reaches the target pH. Slowly add a desired volume of sample to the column. Add at least 10 CV of wash buffer to the column. Slowly add 5 CV of elution buffer (10-50 mM NaAc, pH 3.0-3.5) to the column. Incubate for 3-5 minutes and collect the eluate. Repeat the elution step as needed. Adjust the pH of the eluate to the target pH with neutralization buffer (1M Tris). Determine the protein concentration using a Nanodrop. Replace the buffer containing the antibody with PBS by ultrafiltration.

[0215] Table 4.1 CDR sequences of anti-BDCA-2 hybridoma antibodies (determined using Kabat numbering)

[0216] The heavy chain variable region of hybridoma antibody 17G6A2 is:

[0217] The light chain variable region is:

[0218] The heavy chain variable region of hybridoma antibody 164C11B8 is:

[0219] The light chain variable region is:

[0220] Table 4.2 Constant region sequences of chimeric and humanized antibodies

[0221] Example 4. Functional characterization of anti-human BDCA-2 chimeric antibodies

[0222] 1. Binding activity of anti-human BDCA-2 chimeric antibodies

[0223] The binding activity of the anti-BDCA-2 chimeric antibody to human BDCA-2 ( FIG. 3A ) and cynomolgus monkey BDCA-2 ( FIG. 3B ) was detected using the method disclosed in Section 2.1 of Example 2, with BIIB059 as a control.

[0224] The results are shown in Figures 3A and 3B and Table 5. The EC values ​​of the chimeric antibody 17G6A2_hIgG1 for binding to human BDCA-2 and cynomolgus monkey BDCA-2 were 50 The EC values ​​of chimeric antibody 164C11B8_hIgG1 for binding to human BDCA-2 and cynomolgus monkey BDCA-2 were 87.7 and 79.2 ng / mL, respectively. 50 The EC values ​​of BIIB059 for binding to human and cynomolgus monkey BDCA-2 were 215.4 and 210.0 ng / mL, respectively. 50 175.4 and 134.0 ng / mL respectively.

[0225] Table 5 Binding activity of anti-BDCA-2 antibodies to human BDCA-2 and cynomolgus monkey BDCA-2

[0226] 2. Anti-human BDCA-2 chimeric antibody inhibits CpGA-induced IFNα production in PBMC

[0227] The method disclosed in Section 2.2 of Example 2 was used to detect the activity of the anti-BDCA-2 chimeric antibody obtained in the present application in inhibiting IFNα production, with BIIB059 serving as a control.

[0228] The results are shown in Figures 4A, 4B and Table 6. The EC of the chimeric antibody 17G6A2_hIgG1 for inhibitory activity 50and 1.3 ng / mL, respectively, and the EC of the chimeric antibody 164C11B8_hIgG1 for inhibitory activity was 50 The EC of BIIB059 inhibitory activity was 1.1 ng / mL. 50 It is 2.5ng / mL.

[0229] Table 6. Inhibition of type 1 interferon induced by CpGA in human PBMC cells by anti-BDCA-2 antibodies

[0230] 3. Anti-human BDCA-2 chimeric antibody inhibits immune complex-induced IFNα release in pDCs

[0231] Systemic lupus erythematosus (SLE) patients' serum contains a large number of different anti-autoantibodies, mainly anti-nuclear antibodies. The antigen-antibody complex binds to the Fc receptor (CD32) on the surface of pDC membranes, is then internalized into the cell and activates TLR9, leading to the production of type I interferon. Anti-BDCA-2 antibodies inhibit the production of type I interferon caused by this pathway (PMID: 25762615 EMBO Mol Med. 2015 Apr; 7(4): 464-76). This section investigated whether the obtained chimeric antibody has the function of inhibiting the release of IFNα by pDC.

[0232] The specific method is as follows: pDC cells were sorted according to the instructions of the pDC sorting kit (STEM CELL, 17977). pDC were diluted to 1×10 6Cells / mL, 50 μL per well was placed in a 96-well U-shaped plate. The anti-BDCA-2 chimeric antibody of the present application and the positive control antibody BIIB059 were diluted to 40 μg / ml with RMPI1640 complete medium, and then serially diluted 1:4 with RMPI1640 complete medium to prepare 10 dilution samples. The isotype control antibody was diluted to 40 μg / ml, and then 25 μL of each dilution of the antibody was added to the wells containing pDC cells. Sm / RNP Antigen (Raybiotech, MD-27-0014P): human Anti-RNP Auto-antigen (Raybiotech, MD-14-0513) was mixed at a ratio of 1:2 and incubated at room temperature for 30 minutes to prepare the antigen-antibody complex. Then, 25 μL of the immune complex was added to each well containing pDC cells and placed in a 5% CO2, 37°C incubator for 16 hours. 16 μL of supernatant was added to the corresponding 384 wells. 4 μL of IFNαd2 and 4 μL of crypate antibody mixture (cisbo, 62HIFNAPEG) were added according to the kit instructions. The cells were incubated at room temperature for 2 hours. Relative light units (RLUs) were read on the cell culture plate using a microplate reader. Graphpad Prism 8.0 software was used to analyze the experimental data. The dose-effect curve of the anti-BDCA-2 monoclonal antibody was fitted using a four-parameter regression model, with the logarithm of the anti-BDCA-2 monoclonal antibody concentration as the x-axis and the corresponding RLU value as the y-axis.

[0233] The results are shown in Figures 5A-B and Tables 7A-B. BIIB059, 17G6A2_hIgG1, and 164C11B8_hIgG1 can all block immune complex-induced IFNα production in pDCs. The 17G6A2 chimeric antibody inhibits the activity of EC 50 The EC values ​​of BIIB059 for inhibitory activity were 29.2 ng / mL and 1. 50 The EC of the inhibitory activity of 164C11B8 chimeric antibody was 33.4 ng / mL. 50 The EC of BIIB059 inhibitory activity was 3.6 ng / mL. 50 The pDCs used in Tables 7A and 7B were from different donors.

[0234] Table 7A. Inhibitory activity of anti-BDCA-2 antibodies on type 1 interferon induced by immune complexes in human pDC cells

[0235] Table 7B: Inhibitory activity of anti-BDCA-2 antibodies on type I interferon induced by immune complexes in human pDC cells

[0236] 4. Chimeric antibodies activate FcγRⅢa in a dose-dependent manner

[0237] Clinical studies have shown that anti-BDCA-2 antibodies can eliminate circulating pDCs through ADCC. Anti-BDCA-2 antibody-dependent FcγRⅢa activation was measured by incubating Jurkat-human FcγRⅢa(158V)-NFAT with BDCA-2-expressing cells. The Fab end of the BDCA-2 antibody binds to the target on target cells, while its Fc end binds to the FcγRIIIa receptor on effector cells, thereby activating the NFAT signaling pathway within the effector cells. Luciferase production from NFAT activation is quantified to reflect the antibody's ADCC activity. The specific method is as follows:

[0238] Jurkat-hBDCA-2 cells were centrifuged at 300 g for 5 minutes and the cell concentration was adjusted to 1.2 × 10 6 Cells / mL. 50 μL per well was inoculated into a white opaque plate and used as target cells. The chimeric anti-BDCA-2 antibody, positive control antibody, and negative control antibody IgG1 isotype of this application were diluted with RMPI1640 medium to a concentration of 40 μg / ml, and then diluted 4-fold with the medium. The collected Jurkat-human FcγRⅢa(158V)-NFAT (Jiman Biotechnology (Shanghai) Co., Ltd., GM-C05619) cells were centrifuged at 300 g for 5 minutes, the supernatant was discarded, and the cell concentration was adjusted to 1.5×10 6 cells / mL. 100 μL of cells were added to each well containing target cells. Simultaneously, 50 μL of serially diluted anti-BDCA-2 antibody was added to each well. Induction was performed overnight at 37°C, 5% CO₂, and the cells were allowed to equilibrate at room temperature for at least 15 minutes. 100 μL of luciferase substrate solution (Vazyme, DD1203) was added to each well, mixed, and incubated in the dark for 5 minutes at room temperature. Relative light units (RLUs) were read on the cell culture plate using a microplate reader. Graphpad Prism 8.0 software was used to analyze the data. A four-parameter regression model was used to fit the dose-response curve for the anti-BDCA-2 antibody, with the logarithm of the anti-BDCA-2 antibody concentration as the x-axis and the corresponding RLU values ​​as the y-axis.

[0239] The results are shown in Figure 6 and Table 8. 17G6A2 and 164C11B8 chimeric antibodies can activate Jurkat-human FcγRⅢa(158V)-NFAT reporter cells in a dose-dependent manner. 17G6A2 chimeric antibody activated active EC 50 The EC of the 164C11B8 chimeric antibody activation activity was 15.0 ng / mL. 50 The EC of BIIB059 activation activity was 11.9 ng / mL.50 It is 13.0ng / mL.

[0240] Table 8 Effect of chimeric antibodies on EC activation of Jurkat-human FcγRⅢa(158V)-NFAT reporter cell line 50 value

[0241] 5. Chimeric Antibody Affinity Testing

[0242] A sensor probe designed to recognize human IgG was placed in an Octet Red96e pre-wetted plate. The antibody was diluted to 5000 ng / mL with 0.02% PBST, 0.1% BSA, and 200 μL was added to each well of the black opaque plate. Human BDCA-2 protein was diluted to 400 nM (8800 ng / mL) with 0.02% PBST, 0.1% BSA, and then serially diluted two-fold to obtain a gradient of dilutions. 200 μL was then added to each well of the black opaque plate. The experimental protocol was edited and run using Octet Red96e, and the binding signal was read. Experimental data was analyzed using Octet Data Analysis software, and various kinetic parameters were calculated.

[0243] The results are shown in Table 9. The affinity KD values ​​of the chimeric antibodies 17G6A2_hIgG1 and 164C11B8_hIgG1 were approximately 0.5 nM and 2.2 nM, respectively, and the affinity KD value of the BIIB059 antibody was 1.9 nM.

[0244] Table 9 Chimeric antibody affinity determination values

[0245] Example 5. Construction, expression and purification of humanized anti-BDCA-2 antibodies

[0246] The human germline gene most homologous to the mouse sequence is selected as the acceptor framework, and the CDRs of the mouse sequence (Table 4.1) are transplanted into the human framework. Based on the importance of amino acids, back mutations are performed, meaning that some key amino acids in the transplanted framework region are backmutated to the corresponding mouse amino acids. Several variants of the heavy and light chains are designed, and a complete antibody expression vector is constructed to express the combined heavy and light chains to obtain the humanized antibody protein.

[0247] 1. Construction of humanized anti-BDCA-2 antibody 17G6A2

[0248] The designed humanized heavy and light chain variable region sequences are as follows:

[0249] Humanized antibody numbering and its corresponding heavy and light chain variable region sequence numbering

[0250] 2. Construction of humanized anti-BDCA-2 antibody 164C11B8

[0251] The variable region sequence of the humanized antibody 164C11B8 is shown in the following table:

[0252] Humanized antibody numbers and their corresponding heavy and light chain variable region sequence numbers:

[0253] 3. Expression and purification of constructed humanized antibodies

[0254] Following the disclosure in Example 3, the light and heavy chain variable regions of the humanized antibody were constructed by gene synthesis onto human constant regions (IgG1 / κ, Table 4.2). Expression was performed using Expi293 cells and purification was performed using Protein A. The purified antibody was then buffered by ultrafiltration into PBS.

[0255] Example 6. Binding activity of anti-BDCA-2 humanized antibodies

[0256] 1. Binding activity of anti-BDCA-2 humanized antibodies

[0257] The binding activity of the humanized anti-BDCA-2 antibody obtained in Example 5 to human and cynomolgus monkey BDCA-2 was detected using the method disclosed in Section 2.1 of Example 2, with BIIB059 as a control.

[0258] As shown in Figures 7A, 7B, 7C and 7D and Table 10, all humanized antibodies bound to human BDCA-2 and cynomolgus monkey BDCA-2, and the binding activity was comparable to that of BIIB059.

[0259] Table 10 Binding activity of anti-BDCA-2 antibodies to human BDCA-2 and cynomolgus monkey BDCA-2

[0260] *Average of multiple experiments; NT: not tested. N / A: not applicable, no valid EC was obtained. 50

[0261] 2. Humanized antibodies do not bind to Jurkat cells

[0262] Next, according to the method of Section 2.1 of Example 2, the ability of the humanized antibody obtained in this application to bind to blank Jurkat cells was tested.

[0263] As shown in FIG7E , humanized antibodies 17G6A2 and BIIB059 did not bind to Jurkat cells, and their binding patterns were similar to those of the negative control isotype.

[0264] 3. Humanized Antibody Affinity Testing

[0265] The affinity of the anti-BDCA-2 humanized antibodies was tested using the method disclosed in Section 5 of Example 4. The results are shown in Table 11. The KD values ​​of the 17G6A2 humanized antibody were comparable to those of BIIB059, with KD values ​​of 4.4E-09, 5.9E-09, and 2.9E-09 M for 17G6A2_hzH1L5_hIgG1, 17G6A2_hzH1L6_hIgG1, and 17G6A2_hzH1L7_hIgG1, respectively; the KD value of BIIB059 was 3.9E-09 M.

[0266] Table 11 Affinity determination values ​​of humanized antibodies to human BDCA-2

[0267] Example 7. Functional activity of anti-BDCA-2 humanized antibodies

[0268] 1. Anti-BDCA-2 humanized antibody inhibits IFNα production by PBMC

[0269] The method described in Section 2.2 of Example 2 was used to detect the activity of the anti-BDCA-2 humanized antibody in inhibiting the production of IFNα by human PBMCs, with BIIB059 serving as a control.

[0270] The results are shown in FIG8 and Table 12. Both BIIB059 and 17G6A2 humanized antibodies can block CpGA-induced IFNα production.

[0271] Table 12 Inhibitory activity of anti-BDCA-2 antibodies on CpGA-induced type I interferon in human PBMC cells

[0272] 2. Anti-BDCA-2 humanized antibody inhibits IFNα production by pDCs

[0273] The method in Section 3 of Example 4 was used to detect the activity of the anti-BDCA-2 humanized antibody in inhibiting the production of IFNα by human pDC cells, with BIIB059 as a control.

[0274] The results are shown in Figure 9 and Table 13. Both BIIB059 and 17G6A2 humanized antibodies can block the production of IFNα induced by immune complexes. 17G6A2 humanized antibodies 17G6A2_hzH1L5_hIgG1, 17G6A2_hzH1L6_hIgG1, and 17G6A2_hzH1L7_hIgG1 can block EC 50BIIB059 blocked EC at 0.9 ng / mL, 0.7 ng / mL, and 1.0 ng / mL. 50 It is 2.1ng / mL.

[0275] Table 13 Inhibitory activity of anti-BDCA-2 antibodies on type I interferon induced by immune complexes in human pDC cells

[0276] 3. Binding of anti-BDCA-2 humanized antibody to pDC

[0277] pDCs were isolated according to the instructions of the pDC isolation kit (STEM CELL, 17977). pDCs were diluted to 1×10 5 10 cells / mL, with 50 μL plated per well in a 96-well U-shaped plate. Anti-BDCA-2 humanized antibody, positive control antibody BIIB059, and isotype hIgG1 were diluted to 20 μg / mL in RMPI1640 complete medium. Eight dilutions were prepared, serially diluted 1:5 in RMPI1640 complete medium. Each dilution was added at 50 μL per well to the wells containing pDCs. The cells were incubated at 4°C for 1 hour, pelleted by centrifugation, and washed three times with FACS buffer. An Alexa Flour-647-conjugated anti-human secondary antibody (Invitrogen, Cat. No. A21445) was diluted 1:1000, and the cell pellet was resuspended in 100 μL of the secondary antibody dilution per well. The cells were pipetted to mix thoroughly, and incubated at 4°C for 1 hour. The cells were pelleted by centrifugation, washed three times, and resuspended in 100 μL of FACS buffer per well. The mean fluorescence intensity (MFI) was analyzed by flow cytometry. Graphpad Prism 8.0 software was used to analyze the experimental data. The logarithm of the anti-BDCA-2 monoclonal antibody concentration was used as the x-axis and the corresponding MFI value was used as the y-axis. A four-parameter regression model was used to fit the dose-effect curve of the anti-BDCA-2 monoclonal antibody and calculate the EC 50 .

[0278] The results are shown in Figure 10 and Table 14. EC of the binding activity of 17G6A2 humanized antibody to human pDC 50 The EC value of BIIB059 binding activity to human pDC was 77.6 ng / mL. 50 It is 280.6ng / mL.

[0279] Table 14 Binding activity of anti-BDCA-2 antibodies to human pDC

[0280] 4. Anti-BDCA-2 antibodies do not bind to CLEC4A, CLEC4E, CLEC4D, or CLEC6A

[0281] BDCA-2, CLEC4A, CLEC4E, CLEC4D, and CLEC6A (PMID: 29553870, MAbs. 2018 May / Jun; 10(4): 651-663) belong to the same C-type lectin receptors. Therefore, the inventors continued to explore whether the obtained humanized antibodies have cross-reactivity with other receptors. The following ELISA enzyme-linked adsorption method was used to detect the binding activity of BDCA-2 antibodies to human CLEC4A, CLEC4E, CLEC4D, and CLEC6A. The above proteins were diluted to 1 μg / ml with ELISA coating solution (solarbio, C1055), and 100 μL was added to the plate (corning: 9018) and incubated at 4°C overnight. The next day, the plate was washed 3 times with PBST, blocked with 1% bovine serum albumin (BSA) protein (Sangon Biotech, 9048-46-8) at 37°C for 2 hours, and washed 3 times with PBST. Anti-BDCA-2 antibody was diluted 4-fold starting at a concentration of 10 μg / ml, with 100 μL added to each well. The plate was incubated at 37°C for 1 hour, and the plate was washed three times with PBST. Secondary antibody (abcam, ab98535) was added for 30 minutes, and the plate was washed three times with PBST. Substrate A (BD OptEIA, 51-2606KC) and substrate B (BD OptEIA, 51-2607KC) were mixed at a 1:1 ratio and 100 μL was added to each well. The reaction was continued for 20 minutes, and then stop solution (solarbio, C1058) was added.

[0282] The results are shown in Figures 11A-D. The 17G6A2 humanized antibody prepared in the present application does not bind to proteins CLEC4A, CLEC4E, CLEC4D, and CLEC6A.

[0283] 5. Affinity of humanized antibodies to cyno BDCA-2

[0284] Detection was performed according to the method described in Section 5 of Example 4. The antibody was diluted to 5000 ng / mL with 0.02% PBST, 0.1% BSA. The cynomolgus monkey BDCA-2 protein (acro, CLC-C52H4) was diluted to 400 nM with 0.02% PBST, 0.1% BSA, and then diluted 2-fold to obtain a serial dilution of the cynomolgus monkey BDCA-2 protein. 200 μL was added to each well of a black opaque plate. The experimental protocol was edited and run using Octet Red96e, and the binding signal values ​​were read. The experimental data were analyzed using Octet Data Analysis software, and various kinetic parameters were calculated.

[0285] The results are shown in Table 15. The affinity KD values ​​of humanized antibodies 17G6A2_hzH1L5_hIgG1, 17G6A2_hzH1L6_hIgG1, and 17G6A2_hzH1L7_hIgG1 for binding to cynomolgus monkey BDCA-2 protein were 5.7, 5.6 nM, and 4.8 nM, respectively. The affinity KD value of BIIB059 antibody was 1.1 nM.

[0286] Table 15 Affinity determination values ​​of humanized antibodies to cyno BDCA-2

[0287] 6. 17G6A2 humanized antibody activates FcγRⅢa in a dose-dependent manner

[0288] According to the method of Section 4 of Example 4, the dose-dependent FcγRⅢa activation of 17G6A2 humanized antibody was determined using Jurkat-human FcγRⅢa(158V)-NFAT reporter assay. The results are shown in Figure 12 and Table 16. The activation activity of 17G6A2_hzH1L5_hIgG1, 17G6A2_hzH1L6_hIgG1, and 17G6A2_hzH1L7_hIgG1 antibodies was EC 50 At 4.2, 3.2 and 5.0 ng / ml, BIIB059 activated active EC 50 The value is 4.0ng / ml.

[0289] Table 16 EC of Jurkat-human FcγRⅢa(158V)-NFAT cell line activated by humanized antibodies 50 value

[0290] Example 8. Efficacy of the Antibodies of the Present Invention in Treating SLE Animals

[0291] The immunodeficient NOD scid mice (NOD.CB17-Prkdcscid / NcrCrl, Weitong Lihua Laboratory Animal Technology Co., Ltd., Cat. No. 406) were used to establish the Imiquimod cream (Nanbo, Tianfang Pharmaceutical Co., Ltd., Batch No. 220703001) model of SLE skin lesions in immunodeficient pDC mice. The specific method was: Imiquimod cream was applied to the 1.5 cm × 1.5 cm marked area on the back of the mouse every 12 hours for a total of three doses. The antibody was administered once through the tail vein during the second dose of Imiquimod cream. Human pDC (3×10 5Cells / 100 μl were inoculated into the tail vein 12 hours after the last dose of Imiquimod cream. Endpoint observations included skin pathological changes and hematological markers. Immunohistological staining and flow cytometry data demonstrated that both 17G6A2_hzH1L5_hIgG1 and the active drug BIIB059 inhibited epidermal thickening in mice, reduced the number of pDCs and CD123+ cells in the skin, and suppressed the number of MX1-positive cells downstream of IFNα, with comparable trends.

[0292] Example 9. Antibodies of the present invention induce endocytosis of BDCA2 on pDC in cynomolgus monkeys

[0293] 2 mL EDTA-anticoagulated whole blood samples were collected from four cynomolgus macaques (male, approximately 4 kg, 2 years old, Suzhou Xihua New Drug Development Co., Ltd.) 2 weeks and 1 week before dosing, and the proportion of pDCs in the blood was determined. Based on the pDC proportion and body weight, the macaques were randomly divided into two groups and intravenously injected with 1 mg / kg of 17G6A2_hzH1L5_hIgG1 (experimental group) or BIIB059 (control group). Anticoagulated whole blood samples were collected from each group at 0 hour before dosing, and 1 hour, 6 hours, 3 days, 10 days, 14 days, 21 days, 28 days, and 35 days after dosing. The pDC surface BDCA-2 antigen content and the bound 17G6A2_hzH1L5_hIgG1 or BIIB059 in each blood sample were measured to reflect antibody-induced BDCA-2 protein internalization. The specific method is as follows:

[0294] 1) Direct detection of BDCA-2 expression: Anticoagulated blood samples from cynomolgus monkeys were lysed with erythrocytes (BD Biosciences, Catalog No. 555899) 14 days, 7 days, and 0 hours before administration, and 1 hour, 6 hours, 3 days, 10 days, 14 days, 21 days, 28 days, and 35 days after administration. Anti-CD14-APC / Cy7 (Biolegend, Catalog No. 301820), anti-CD20-PE (Biolegend, Catalog No. 302306), anti-HLA-DR-BV510 (Biolegend, Catalog No. 307646), and anti-CD123-FITC (BD Biosciences, Catalog No. 558663) were used to detect cells in peripheral blood samples of cynomolgus monkeys. - CD20 - HLA-DR + CD123 +pDCs were detected using 17G6A2_hzH1L5_hIgG1 or BIIB059 directly labeled with AF647 at various time points to detect BDCA2 on the surface of pDCs. Cells were harvested using CytoFlex and data analyzed on CytExpert. The results are shown in Figure 13.

[0295] 2) Indirect labeling method to detect 17G6A2_hzH1L5_hIgG1 or BIIB059 bound to the pDC surface

[0296] Anticoagulated blood samples were collected 14 and 7 days before dosing, and after erythrocyte lysis, 40 μg / mL of 17G6A2_hzH1L5_hIgG1 or BIIB059 was added to test their maximum binding capacity on the pDC surface. pDCs were stained and detected according to the method in 1). 17G6A2_hzH1L5_hIgG1 or BIIB059 bound to the pDC surface was indirectly detected using an AF647-labeled anti-human IgG secondary antibody.

[0297] Anticoagulated blood samples were collected from cynomolgus monkeys at 0 hour before dosing, and at 1 hour, 6 hours, 3 days, 10 days, 14 days, 21 days, 28 days, and 35 days after dosing. After erythrocyte lysis, pDCs were stained according to the method described in 1). 17G6A2_hzH1L5_hIgG1 or BIIB059 bound to the pDC surface were indirectly detected using an AF647-labeled anti-human IgG secondary antibody. Cells were harvested using CytoFlex and analyzed on CytExpert. The results are shown in Figure 14.

[0298] As shown in Figure 13 (direct labeling method), BDCA2 expression was virtually undetectable on cynomolgus monkey pDCs from 1 hour to 3 days after administration of 17G6A2_hzH1L5_hIgG1 or BIIB059, indicating that BDCA2 on the pDC cell surface was occupied by 17G6A2_hzH1L5_hIgG1 or BIIB059, or that BDCA2 was internalized. In the BIIB059-treated group, BDCA2 expression was re-detected on the pDC cell surface 10 and 28 days after administration, respectively, whereas BDCA2 expression remained undetectable in the 17G6A2_hzH1L5_hIgG1-treated group until 35 days after administration. Between 10 and 28 days after administration, BDCA-2 was no longer occupied by the drug and returned to the cell surface. Therefore, AF647-labeled BIIB059 could bind to unoccupied BDCA-2, resulting in the detection of BDCA-2 expression. However, the 17G6A2_hzH1L5_hIgG1-administered group may still occupy BDCA-2 and remain in the cells, so no signal can be detected.

[0299] The results are shown in Figure 14 (indirect labeling method). When 17G6A2_hzH1L5_hIgG1 or BIIB059 was added to anticoagulated blood collected 2 weeks and 1 week before administration, the corresponding antibodies 17G6A2_hzH1L5_hIgG1 or BIIB059, which bind to BDCA2, were detected on pDCs, indicating that pDCs express high levels of BDCA2. However, after administration, 17G6A2_hzH1L5_hIgG1 or BIIB059 was almost undetectable on pDCs.

[0300] In summary, 17G6A2_hzH1L5_hIgG1 and BIIB059 induced BDCA2 internalization on the surface of pDCs in cynomolgus monkeys, and the induced internalization or inhibition of BDCA2 by 17G6A2_hzH1L5_hIgG1 was more sustained than that by BIIB059.

[0301] Description of Sequence Listing

[0302] Chimeric antibody 17G6A2

[0303] Heavy chain:

[0304] Light chain:

[0305] Chimeric antibody 164C11B8

[0306] Heavy chain:

[0307] Light chain:

[0308] Corresponding heavy and light chain sequences of humanized antibodies

Claims

1. An antibody or antigen-binding fragment thereof that binds to BDCA-2, comprising: 1) three heavy chain CDRs (HCDR1, HCDR2, HCDR3) contained in the heavy chain variable region as shown in SEQ ID NO:7 and / or three light chain CDRs (LCDR1, LCDR2, LCDR3) contained in the light chain variable region as shown in SEQ ID NO:8; or 2) three heavy chain CDRs (HCDR1, HCDR2, HCDR3) contained in the heavy chain variable region as shown in SEQ ID NO: 17 and / or three light chain CDRs (LCDR1, LCDR2, LCDR3) contained in the light chain variable region as shown in SEQ ID NO:

18.

2. The antibody or antigen-binding fragment thereof that binds to BDCA-2 according to claim 1, comprising heavy chain variable region CDRs (HCDR1, HCDR2, HCDR3) and / or light chain variable region CDRs (LCDR1, LCDR2, LCDR3), wherein 1) HCDR1 comprises the sequence shown in SEQ ID NO:1, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:1, or consists of SEQ ID NO:1; HCDR2 comprises the sequence shown in SEQ ID NO:2, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:2, or consists of SEQ ID NO:2; HCDR3 comprises the sequence shown in SEQ ID NO:3, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:3, or consists of SEQ ID NO:3; LCDR1 comprises the sequence shown in SEQ ID NO:4, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:4, or consists of SEQ ID NO:4; LCDR2 comprises the sequence shown in SEQ ID NO:5, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:5, or consists of SEQ ID NO:5; NO:5; and LCDR3 comprises a sequence as shown in SEQ ID NO:6 or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions or any combination thereof relative to SEQ ID NO:6, or consists of SEQ ID NO:6; or 2) HCDR1 comprises the sequence shown in SEQ ID NO: 11, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 11, or consists of SEQ ID NO: 11; HCDR2 comprises the sequence shown in SEQ ID NO: 12, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 12, or consists of SEQ ID NO: 12; HCDR3 comprises the sequence shown in SEQ ID NO: 13 A sequence or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 13, or consisting of SEQ ID NO: 13; LCDR1 comprises a sequence as shown in SEQ ID NO: 14, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 14, or consisting of SEQ ID NO: 14; LCDR2 comprises a sequence as shown in SEQ ID NO: 15, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 15, or consisting of SEQ ID NO: 15; and LCDR3 comprises a sequence as shown in SEQ ID NO: 16, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 16, or consisting of SEQ ID NO:

16.

3. The antibody or antigen-binding fragment thereof that binds to BDCA-2 according to claim 1 or 2, comprising a heavy chain variable region and / or a light chain variable region, wherein: 1) the heavy chain variable region comprises or consists of the amino acid sequence as shown in SEQ ID NO: 7 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 7, and the light chain variable region comprises or consists of the amino acid sequence as shown in SEQ ID NO: 8 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 8; 2) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 17 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 17, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 18 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 18; 3) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 19, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 22, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 22; 4) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 19 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 23 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 23; 5) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 19 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 24 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:

24. or consisting of an amino acid sequence that is at least 90% identical; 6) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 19 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 19, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 25 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 25; 7) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 20 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 22 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 22; 8) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 20 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 23 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 23; 9) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 20 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 24 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 24; 10) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 20 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 25 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 25; 11) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 21 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 22 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 22; 12) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 21 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 23 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 23; 13) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 21 or a sequence similar to SEQ ID NO: NO:21, wherein the light chain variable region comprises or consists of an amino acid sequence as set forth in SEQ ID NO:24 or an amino acid sequence at least 90% identical to the amino acid sequence of SEQ ID NO:24; 14) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 21 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 25 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 25; 15) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 26 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 30 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 30; 16) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 26 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 31 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 31; 17) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 26 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 32 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 32; 18) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 27 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 30 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 30; 19) the heavy chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 27 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 31 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 31; 20) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 27 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 27, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 32 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 32; 21) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 28 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 30 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 30; 22) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 28 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 31 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 31; 23) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 28 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 32 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 32; 24) the heavy chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 29 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence of SEQ ID NO: 30 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 30; 25) the heavy chain variable region comprises or consists of the amino acid sequence as shown in SEQ ID NO: 29 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence as shown in SEQ ID NO: 31 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 31; or 26) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 29 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 29, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 32 or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:

32.

4. The antibody or antigen-binding fragment thereof that binds to BDCA-2 according to any one of claims 1 to 3, comprising a heavy chain and / or a light chain, wherein: 1) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO: 33, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 33, or consists of SEQ ID NO: 33, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO: 34, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 34, or consists of SEQ ID NO: 34; 2) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO: 35, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 35, or consists of SEQ ID NO: 35, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO: 36, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 36, or consists of SEQ ID NO: 36; 3) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO: 37, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 37, or consists of SEQ ID NO: 37, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO: 38, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 38, or consists of SEQ ID NO: 38; 4) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:37, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:39, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; 5) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:37, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:40, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:40, or consists of SEQ ID NO:40; 6) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:37, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:41, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41; 7) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:42, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:38, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38; 8) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:42, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:39, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; 9) the heavy chain comprises the amino acid sequence of SEQ ID NO: 42, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 42, or consists of SEQ ID NO: 42, and the light chain comprises the amino acid sequence of SEQ ID NO: 40, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:

40. an amino acid sequence having at least 90% identity with, or consisting of, SEQ ID NO: 40; 10) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:42, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:41, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41; 11) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:43, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:38, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38; 12) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:43, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:39, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; 13) the heavy chain comprises the amino acid sequence as set forth in SEQ ID NO:43, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43, and the light chain comprises the amino acid sequence as set forth in SEQ ID NO:40, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:40, or consists of SEQ ID NO:40; 14) The heavy chain comprises the amino acid sequence shown in SEQ ID NO: 43, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO: 43, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 41, or an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 41, or consists of SEQ ID NO:

41.

5. The antibody or antigen-binding fragment thereof that binds to BDCA-2 of any one of claims 1 to 4, wherein the antigen-binding fragment is a Fab, Fab'-SH, Fv, scFv, or (Fab')2 fragment.

6. An isolated polynucleotide molecule encoding the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5. A vector comprising the polynucleotide molecule according to claim 6 . A host cell comprising the vector according to claim 7 or the polynucleotide molecule according to claim 6.

9. A conjugate comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5 and a conjugated portion, wherein the conjugated portion is another molecule; preferably, the conjugated portion is a radioactive isotope, a fluorescent substance, a luminescent substance, a colored substance or an enzyme.

10. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5, the polynucleotide molecule according to claim 6, the vector according to claim 7, the host cell according to claim 8, the conjugate according to claim 9, and a pharmaceutically acceptable carrier.

11. A method for preparing an antibody or antigen-binding fragment thereof that binds to BDCA-2, the method comprising culturing a host cell comprising a polynucleotide molecule encoding the antibody or antigen-binding fragment thereof of any one of claims 1 to 5 under conditions suitable for expression of the antibody, optionally further comprising recovering the antibody or antigen-binding fragment thereof from the host cell.

12. Use of the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5, or the polynucleotide molecule according to claim 6, or the vector according to claim 7, or the host cell according to claim 8, or the conjugate according to claim 9, or the composition according to claim 10 in the preparation of a medicament for treating a disease suffered by a subject.

13. The method of claim 12, wherein the disease is an autoimmune disease or cancer, such as autoimmune diseases such as systemic lupus erythematosus (SLE), scleroderma, polymyositis, dermatomyositis, psoriasis, Sjoegren's syndrome, rheumatoid arthritis, Graves' disease and Hashimoto's disease; breast tumors, ovarian cancer, multiple myeloma (MM), etc.

14. A method for reducing or eliminating circulating pDC cells, comprising administering to the subject an effective amount of the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5, the polynucleotide molecule according to claim 6, the vector according to claim 7, the host cell according to claim 8, the conjugate according to claim 9, or the pharmaceutical composition according to claim 10.

15. A method for preventing and / or treating tumors or autoimmune diseases in a subject, the method comprising administering to a subject in need thereof an effective amount of the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5, the polynucleotide molecule according to claim 6, the vector according to claim 7, the host cell according to claim 8, the conjugate according to claim 9, or the pharmaceutical composition according to claim 10.

16. A kit comprising the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5 or the conjugate according to claim 9.

17. A method for detecting the presence or level of BDCA-2 in a sample, comprising the steps of contacting the antibody or antigen-binding fragment thereof according to any one of claims 1 to 5 or the conjugate according to claim 9 with the sample, and detecting whether the antibody or antigen-binding fragment thereof or the conjugate forms a complex with BDCA-2.

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