Anti-kappa light chain antibody and use thereof

Abstract

The application discloses an antibody against kappa type light chain or a reagent and kit for detecting kappa type light chain, and relates to the field of antibodies. The antibody against kappa type light chain disclosed by the application comprises a heavy chain complementarity determining region and a light chain complementarity determining region, the antibody provides an important raw material source for the detection of kappa type light chain, and has good affinity or activity.

Description

Technical Field

[0001] This invention relates to the field of antibody technology, and more specifically, to an anti-κ light chain antibody and its application. Background Technology

[0002] Immunoglobulin light chains consist of approximately 214 amino acid residues, typically contain no carbohydrates, and have a molecular weight of about 24 kDa. Each light chain contains two cyclic peptides linked by intrachain disulfide bonds. Light chains can be classified into κ (Kappa) and λ (Lambda) types. Each light chain can only belong to one of these two types, not both. The differences between κ and λ types are mainly reflected in the amino acid sequence and the position of the disulfide chains. The κ / λ ratio varies among different species, with a normal human serum κ:λ ratio of approximately 2:1. Studies of gene expression in some species have shown that Kappa gene rearrangements occur earlier than Lambda gene rearrangements, which may be one reason why κ types are more likely to pair with heavy chains. Light chains are small protein molecules that can freely pass through the glomerular basement membrane and are reabsorbed back into the bloodstream in the renal tubules. Therefore, only a small amount of light chains are present in the urine of normal individuals. However, when immunoglobulin synthesis is abnormally activated, the synthesis rate of both heavy and light chains increases rapidly, resulting in a severe excess of light chains.

[0003] In patients with multiple myeloma, approximately 20% secrete only free light chains (FLCs), while 50% secrete both monoclonal immunoglobulins and monoclonal urinary light chains; the former has a poorer prognosis. Quantitative detection of different types of light chains is helpful in diagnosing macroglobulinemia and connective tissue diseases (such as rheumatoid arthritis and systemic lupus erythematosus). Furthermore, blood light chains can also be elevated in infections, acute and chronic hepatitis, and cirrhosis, but generally, both κ and λ are elevated simultaneously; patients with kidney disease and diabetes may also show elevated κ and λ in their urine. Therefore, detecting κ-type light chains is of great significance for early diagnosis, prognosis assessment, medication guidance, and research on pathogenesis.

[0004] Immunological detection methods are one of the best choices for detecting light chain peptides. Examples of immunological detection methods include colloidal gold immunochromatography, fluorescence immunochromatography, and biochemical immunoturbidimetry. These methods are based on the specific reaction between antibodies and antigens, and utilize labeled substances (such as colloidal gold, fluorescence, latex, etc.) to amplify and display the detected signal. Similar immunological detection methods include radioimmunoassay and chemiluminescence immunoassay.

[0005] The aforementioned immunological detection methods all require antibodies targeting the κ light chain. Therefore, there is a strong demand in the art for anti-κ light chain antibodies with good performance. Summary of the Invention

[0006] This application provides an anti-κ light chain antibody or its antigen-binding fragment, which provides an important source of raw materials for the detection of κ light chains and has good activity or affinity.

[0007] To achieve the above objectives, according to one aspect of the present invention, an anti-κ light chain antibody or an antigen-binding fragment thereof is provided, the anti-κ light chain antibody or the antigen-binding fragment thereof comprising three complementary determining regions having a heavy chain variable region having any one of the amino acid sequences SEQ ID NO: 20, 21 and three complementary determining regions having a light chain variable region having any one of the amino acid sequences SEQ ID NO: 24, 25, 26.

[0008] To achieve the above objective, according to a second aspect of the present invention, an anti-κ light chain antibody or an antigen-binding fragment thereof is provided, said anti-κ light chain antibody or antigen-binding fragment thereof comprising the following complementarity-determining region:

[0009] HCDR1, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:1;

[0010] HCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:2;

[0011] HCDR3, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:3;

[0012] LCDR1, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:4 and 17;

[0013] LCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:5; and

[0014] LCDR3, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:6 and 18.

[0015] To achieve the above objectives, according to a third aspect of the present invention, an anti-κ light chain antibody or an antigen-binding fragment thereof is provided, comprising a heavy chain variable region and / or a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is as shown in any one of SEQ ID NO: 20 and 21; and the amino acid sequence of the light chain variable region is as shown in any one of SEQ ID NO: 24, 25, and 26.

[0016] To achieve the above objectives, according to a fourth aspect of the present invention, an anti-κ light chain antibody or an antigen-binding fragment thereof is provided, comprising a heavy chain and / or a light chain, wherein the amino acid sequence of the heavy chain is as shown in any one of SEQ ID NO: 22, 23; and the amino acid sequence of the light chain is as shown in any one of SEQ ID NO: 27, 28, 29.

[0017] To achieve the above objectives, according to a fifth aspect of the present invention, an antibody conjugate is provided, the antibody conjugate comprising the above-described anti-κ light chain antibody or its antigen-binding fragment.

[0018] To achieve the above objectives, according to a sixth aspect of the present invention, a reagent or kit is provided, the reagent or kit comprising the above-described anti-κ light chain antibody or its antigen-binding fragment or the above-described antibody conjugate.

[0019] To achieve the above objectives, according to a seventh aspect of the present invention, a method for detecting κ-type light chains is provided, comprising: a) contacting the aforementioned anti-κ-type light chain antibody or its antigen-binding fragment, antibody conjugate, or reagent or kit with κ-type light chains in a sample to be tested under conditions sufficient to induce an antibody / antigen binding reaction to form an immune complex; and b) detecting the presence of the immune complex, the presence of which indicates the presence of the antigen in the test sample.

[0020] To achieve the above objectives, according to an eighth aspect of the present invention, a nucleic acid is provided that encodes the aforementioned anti-κ light chain antibody or its antigen-binding fragment.

[0021] To achieve the above objectives, according to a ninth aspect of the present invention, a vector is provided, the vector comprising the above-described nucleic acid.

[0022] To achieve the above objectives, according to a tenth aspect of the present invention, a cell is provided, said cell comprising the above-described nucleic acid, vector, or expressing the above-described anti-κ light chain antibody or its antigen-binding fragment.

[0023] To achieve the above objectives, according to an eleventh aspect of the present invention, a method for preparing the above-described anti-κ light chain antibody or its antigen-binding fragment is provided, the method comprising culturing the above-described cells.

[0024] To achieve the above objectives, according to the twelfth aspect of the present invention, the use of the above-described anti-κ light chain antibody or its antigen-binding fragment, antibody conjugate, reagent or kit in the preparation of products for detecting κ light chains is provided. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1The results of reductive SDS-PAGE for Anti-KAPPA 12G3 Rmb1 to Anti-KAPPA 12G3 Rmb6. Detailed Implementation

[0027] In a first aspect, embodiments of the present invention provide an anti-κ light chain antibody or its antigen-binding fragment thereof, wherein the anti-κ light chain antibody or its antigen-binding fragment comprises three complementary determining regions having any one of the heavy chain variable regions of amino acid sequences SEQ ID NO:20, 21 and three complementary determining regions having any one of the light chain variable regions of amino acid sequences SEQ ID NO:24, 25, 26.

[0028] It should be noted that HCDR1, HCDR2, and HCDR3 are amino acid sequences identical to those of HCDR1, HCDR2, and HCDR3 in the same heavy chain variable region defined in the anti-κ light chain antibody or its antigen-binding fragment as described in the first aspect, and LCDR1, LCDR2, and LCDR3 are amino acid sequences identical to those of LCDR1, LCDR2, and LCDR3 in the same light chain variable region defined in the anti-κ light chain antibody or its antigen-binding fragment as described in the first aspect.

[0029] For example, HCDR1, HCDR2, and HCDR3 are amino acid sequences consistent with HCDR1, HCDR2, and HCDR3 of the heavy chain variable region shown in SEQ ID NO:20; LCDR1, LCDR2, and LCDR3 are amino acid sequences consistent with LCDR1, LCDR2, and LCDR3 of the light chain variable region shown in SEQ ID NO:24.

[0030] In this invention, the term "antibody" is used in the broadest sense, and may include full-length monoclonal antibodies, bispecific or multispecific antibodies, and chimeric antibodies, as long as they exhibit the desired biological activity.

[0031] In this invention, the terms "complementarity-determining region," "CDR," or "CDRs" refer to highly variable regions of the heavy and light chains of immunoglobulins, specifically regions containing one or more, or even all, of the major amino acid residues that contribute to the binding of an antibody or antigen-binding fragment to the antigen or epitope it recognizes. In specific embodiments of this invention, CDRs refer to highly variable regions of the heavy and light chains of the antibody.

[0032] In this invention, the heavy chain complementarity determination region is represented by HCDR, which includes HCDR1, HCDR2 and HCDR3; the light chain complementarity determination region is represented by LCDR, which includes LCDR1, LCDR2 and LCDR3.

[0033] Methods for defining CDRs are well-known in the art and include: Kabat definition, Chothia definition, IMGT definition, Contact definition, and AbM definition. As described herein, "Kabat definition" refers to the definition system described in Kabat et al., USDept. of Health and Human Services, "Sequence of Proteins of Immunological Interest" (1983). "Chothia definition" is found in Chothia et al., J Mol Biol 196:901-917 (1987). Other CDR definition methods may not strictly follow one of the above schemes but will still overlap with at least a portion of the CDR region defined by Kabat, although they may be shortened or lengthened based on predictions or experimental results of specific residues or residue groups. Exemplary defined CDRs are listed in Table 1 below; definitions vary slightly in different literature. Given the amino acid sequence of the variable region of an antibody, those skilled in the art can routinely determine which residues contain a specific CDR. It should be noted that CDRs defined by other methods, not limited to those in Table 1, are also within the scope of this disclosure.

[0034] Table 1: CDR Definition 1

[0035]

[0036]

[0037] 1 The CDRs defined in Table 1 are numbered according to the Kabat numbering system (see below), with amino acid numbers on the heavy chain represented by "H + number" and amino acid numbers on the light chain represented by "L + number". Those skilled in the art can readily map this Kabat numbering system to any variable region sequence without relying on any experimental data outside the sequence itself. As used herein, "Kabat numbering" refers to the numbering system described by Kabat et al., USD ept. of Health and Human Services, "Sequence of Proteins of Immunological Interest" (1983).

[0038] 2 As used in Table 1, “AbM” with a lowercase “b” refers to the CDR defined by the “AbM” antibody modeling software of Oxford Molecular.

[0039] 3If neither H35A nor H35B exists, then CDR-H1 ends at bit 35; if only H35A exists, then CDR-H1 ends at bit 35A; if both H35A and H35B exist, then CDR-H1 ends at bit 35B.

[0040] 4 If neither H35A nor H35B exists, then CDR-H1 ends at bit 32; if only H35A exists, then CDR-H1 ends at bit 33; if both H35A and H35B exist, then CDR-H1 ends at bit 34.

[0041] 5 If neither H35A nor H35B exists, then CDR-H1 ends at bit 33; if only H35A exists, then CDR-H1 ends at bit 34; if both H35A and H35B exist, then CDR-H1 ends at bit 35.

[0042] According to embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 or LCDR3 is defined by any one or a combination of systems such as Kabat, Chothia, IMGT, AbM or Contact.

[0043] In some optional embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the Kabat system.

[0044] In some optional embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the Chothia system.

[0045] In some alternative embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the IMGT system.

[0046] In some optional embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the AbM system.

[0047] In some alternative embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the Contact system.

[0048] In some alternative embodiments of the present invention, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by a combination of Kabat, Chothia, IMGT, AbM, or Contact systems.

[0049] According to embodiments of the present invention, the Kabat numbering positions corresponding to the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, or LCDR3 defined by the Kabat, Chothia, AbM, or IMGT systems are as follows:

[0050] CDR Kabat AbM IMGT Chothia HCDR1 H31~H35 H26~H35 H26~H33 H26~H32 HCDR2 H50~H65 H50~H58 H51~H57 H52~H56 HCDR3 H95~H102 H95~H102 H93~H102 H95~H102 LCDR1 L24~L34 L24~L34 L27~L32 L24~L34 LCDR2 L50~L56 L50~L56 L50~L51 L50~L56 LCDR3 L89~L97 L89~L97 L89~L97 L89~L97

[0051] According to embodiments of the present invention, the antibody or its antigen-binding fragment includes the following complementarity-determining region:

[0052] HCDR1, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:1;

[0053] HCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:2;

[0054] HCDR3, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:3;

[0055] LCDR1, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:4 and 17;

[0056] LCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:5; and

[0057] LCDR3, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:6 and 18.

[0058] Secondly, embodiments of the present invention provide an anti-κ light chain antibody or its antigen-binding fragment, wherein the anti-κ light chain antibody or its antigen-binding fragment includes the following complementarity-determining region:

[0059] HCDR1, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:1;

[0060] HCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:2;

[0061] HCDR3, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:3;

[0062] LCDR1, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:4 and 17;

[0063] LCDR2, which contains, or is composed of, the amino acid sequence shown in SEQ ID NO:5; and

[0064] LCDR3, which contains, or is composed of, the amino acid sequences shown in SEQ ID NO:6 and 18.

[0065] According to an embodiment of the present invention, the HCDRs and LCDRs are defined by the Kabat system.

[0066] In this invention, the "frame region" or "FR" region includes the heavy chain frame region and the light chain frame region, referring to the regions in the antibody heavy chain variable region and light chain variable region other than the CDR; wherein, the heavy chain frame region can be further subdivided into adjacent regions separated by the CDR, including the HFR1, HFR2, HFR3 and HFR4 frame regions; the light chain frame region can be further subdivided into adjacent regions separated by the CDR, including the LFR1, LFR2, LFR3 and LFR4 frame regions.

[0067] In this invention, the heavy chain variable region is obtained by connecting the following numbered CDRs and FRs in the following combination: HFR1-HCDR1-HFR2-HCDR2-HFR3-HCDR3-HFR4; the light chain variable region is obtained by connecting the following numbered CDRs and FRs in the following combination: LFR1-LCDR1-LFR2-LCDR2-LFR3-LCDR3-LFR4.

[0068] In an optional embodiment, the anti-κ light chain antibody or its antigen-binding fragment described in the first or second aspect further comprises at least one of HFR1, HFR2, HFR3, HFR4, LFR1, LFR2, LFR3 and LFR4;

[0069] The HFR1 includes / is such as SEQ ID NO:7 or an amino acid sequence having at least 80% identity with it;

[0070] The HFR2 includes / is such as SEQ ID NO:8 or an amino acid sequence having at least 80% identity with it;

[0071] The HFR3 includes / is, for example, SEQ ID NO:9 or an amino acid sequence having at least 80% identity with it;

[0072] The HFR4 includes / is, for example, SEQ ID NO:10 or an amino acid sequence having at least 80% identity with it;

[0073] The LFR1 includes / such as SEQ ID NO:11 or an amino acid sequence having at least 80% identity with it;

[0074] The LFR2 includes / is, for example, SEQ ID NO:12 or an amino acid sequence having at least 80% identity with it;

[0075] The LFR3 includes / is, for example, SEQ ID NO:13 or an amino acid sequence having at least 80% identity with it;

[0076] The LFR4 includes / such as SEQ ID NO:14 or an amino acid sequence having at least 80% identity with it.

[0077] It should be noted that, in other embodiments, the amino acid sequences of each frame region of the anti-κ light chain antibody or its antigen-binding fragment provided by the present invention may have at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with the corresponding frame regions (SEQ ID NO: 7, 8, 9, 10, 11, 12, 13, or 14) mentioned above.

[0078] In an optional embodiment, the HFR2 includes / as shown in SEQ ID NO:19, an amino acid sequence.

[0079] In an optional embodiment, the anti-κ light chain antibody or its antigen-binding fragment has a KD ≤ 10. -7 M, KD≤10 -8 M, KD≤10 -9 M, KD≤10 -10 M, KD≤10 -11 M, KD≤10 -12 M, KD≤10 -13 M, KD≤10 -14 M or KD≤10 -15 M binds to the κ-type light chain with affinity.

[0080] There are many methods for determining antibody affinity (KD), which can be categorized into thermodynamic detection methods, kinetic detection methods, and dynamic equilibrium detection methods based on their detection principles. Common thermodynamic detection methods include isothermal titration calorimetry (ITC); common kinetic detection methods include surface plasmon resonance (SPR) and biomembrane optical interferometry (BLI); and common dynamic equilibrium detection methods include enzyme-linked immunosorbent assay (ELISA).

[0081] In an optional implementation, KD is measured using a kinetic detection method; alternatively, surface plasmon resonance, for example, by using a method such as The system's biosensor system.

[0082] Thirdly, embodiments of the present invention provide an anti-κ light chain antibody or its antigen-binding fragment, comprising a heavy chain variable region and / or a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is as shown in any one of SEQ ID NO: 20 and 21, and the amino acid sequence of the light chain variable region is as shown in any one of SEQ ID NO: 24, 25, and 26.

[0083] In an optional implementation, the heavy chain variable region and the light chain variable region described in the first or third aspect above are selected from any combination of the following:

[0084]

[0085]

[0086] In an optional embodiment, the antibody or antigen-binding fragment thereof described in the first, second, or third aspect above includes a heavy chain variable region and a light chain variable region in any combination of the following:

[0087] combination Heavy chain variable region Light chain variable region 1 SEQ ID NO:20 SEQ ID NO:24 2 SEQ ID NO:20 SEQ ID NO:25 3 SEQ ID NO:20 SEQ ID NO:26 4 SEQ ID NO:21 SEQ ID NO:24 5 SEQ ID NO:21 SEQ ID NO:25 6 SEQ ID NO:21 SEQ ID NO:26 .

[0088] In an optional embodiment, the anti-κ light chain antibody or its antigen-binding fragment described in the first, second or third aspect above further includes a constant region.

[0089] In an optional implementation, the constant region includes a heavy chain constant region and / or a light chain constant region.

[0090] In an optional implementation, the heavy chain constant region is selected from any one of the heavy chain constant regions of IgG, IgA, IgM, IgE, and IgD, or a combination of multiple constant region segments.

[0091] In an optional embodiment, the heavy chain constant region includes CH1 of IgG, the hinge region of IgG, CH2 of IgM, CH3 of IgM, and / or CH4 of IgM.

[0092] In an optional implementation, the IgG is selected from IgG1, IgG2, IgG3 or IgG4.

[0093] In an optional implementation, the light chain constant region is selected from the κ-type or λ-type light chain constant region.

[0094] In an optional implementation, the species source of the constant region is cattle, horses, dairy cows, pigs, sheep, rats, mice, dogs, cats, rabbits, donkeys, deer, mink, chickens, ducks, geese, turkeys, fighting cocks, or humans.

[0095] In an optional implementation, the species source of the constant region is mice.

[0096] In an optional embodiment, the heavy chain constant region sequence (CH) is as shown in SEQ ID NO:15, and the light chain constant region sequence (CL) is as shown in SEQ ID NO:16.

[0097] It should be noted that, in other embodiments, the constant region sequence may have at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with the aforementioned constant region (SEQ ID NO: 15 or 16).

[0098] In an optional embodiment, the antigen-binding fragment is selected from any one of the antibody's F(ab)2, F(ab')2, Fab', Fab, Fv, and scFv.

[0099] The antigen-binding fragments of the aforementioned antibodies typically possess the same binding specificity as the source antibody. Those skilled in the art will readily understand, based on the description of this invention, that the antigen-binding fragments of the aforementioned antibodies can be obtained, for example, by enzymatic digestion (including pepsin or papain) and / or by chemical reduction of disulfide bonds. Based on the complete antibody structure disclosed in this invention, those skilled in the art can readily obtain the aforementioned antigen-binding fragments.

[0100] The antigen-binding fragments of the aforementioned antibodies can also be obtained by recombinant genetic techniques known to those skilled in the art or by synthesizing, for example, automated peptide synthesizers sold by Applied BioSystems.

[0101] Fourthly, the present invention provides an anti-κ light chain antibody or an antigen-binding fragment thereof, comprising a heavy chain and / or a light chain, wherein the amino acid sequence of the heavy chain is as shown in any one of SEQ ID NO:22 or 23, and the amino acid sequence of the light chain is as shown in any one of SEQ ID NO:27, 28, or 29.

[0102] In an optional embodiment, the antibody or its antigen-binding fragment described in the first, second, third, or fourth aspect above includes any combination of the heavy chain and light chain:

[0103] combination Heavy chain Light chain 1 SEQ ID NO:22 SEQ ID NO:27 2 SEQ ID NO:22 SEQ ID NO:28 3 SEQ ID NO:22 SEQ ID NO:29 4 SEQ ID NO:23 SEQ ID NO:27 5 SEQ ID NO:23 SEQ ID NO:28 6 SEQ ID NO:23 SEQ ID NO:29

[0104] Fifthly, the present invention provides an antibody conjugate comprising the above-described anti-κ light chain antibody or its antigen-binding fragment.

[0105] In an optional embodiment, the antibody conjugate further includes biotin or a biotin derivative conjugated to the anti-κ light chain antibody or its antigen-binding fragment.

[0106] In an optional embodiment, the antibody conjugate further includes a marker conjugated to the anti-κ light chain antibody or its antigen-binding fragment.

[0107] In an optional implementation, the aforementioned marker refers to a type of substance that has properties such as luminescence, color development, and radioactivity that can be directly observed by the naked eye or detected or probed by instruments. Through these properties, qualitative or quantitative detection of the corresponding target can be achieved.

[0108] In optional embodiments, the markers include, but are not limited to, fluorescent dyes, enzymes, radioisotopes, chemiluminescent reagents, and nanoparticle markers.

[0109] In practical use, those skilled in the art can select appropriate markers according to the detection conditions or actual needs. Regardless of the marker used, it falls within the protection scope of this invention.

[0110] In optional embodiments, the fluorescent dyes include, but are not limited to, fluorescein dyes and their derivatives (e.g., including but not limited to fluorescein isothiocyanate (FITC), hydroxyfluorescein (FAM), tetrachlorofluorescein (TET), etc., or their analogues), rhodamine dyes and their derivatives (e.g., including but not limited to red rhodamine (RBITC), tetramethylrhodamine (TAMRA), rhodamine B (TRITC), etc., or their analogues), and Cy series dyes and their derivatives (e.g., including but not limited to Cy2, Cy3, Cy3B, Cy3.5, C...). y5, Cy5.5, Cy3 and other similar substances), Alexa series dyes and their derivatives (including but not limited to Alexa Fluor 350, 405, 430, 488, 532, 546, 555, 568, 594, 610, 33, 647, 680, 700, 750 and other similar substances) and protein dyes and their derivatives (including but not limited to phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC), polydiophytoxanthin-chlorophyll protein (preCP) and other similar substances).

[0111] In optional embodiments, the enzymes include, but are not limited to, horseradish peroxidase, alkaline phosphatase, β-galactosidase, glucose oxidase, carbonic anhydrase, acetylcholinesterase, and glucose-6-phosphate dehydrogenase.

[0112] In optional embodiments, the radioactive isotopes include, but are not limited to, 212Bi, 131I, 111In, 90Y, 186Re, 211At, 125I, 188Re, 153Sm, 213Bi, 32P, 94mTc, 99mTc, 203Pb, 67Ga, 68Ga, 43Sc, 47Sc, 110mIn, 97Ru, 62Cu, 64Cu, 67Cu, 68Cu, 86Y, 88Y, 121Sn, 161Tb, 166Ho, 105Rh, 177Lu, 172Lu, and 18F.

[0113] In optional embodiments, the chemiluminescent reagents include, but are not limited to, luminol and its derivatives, luciferin, fluorescein and its derivatives, ruthenium bipyridine and its derivatives, acridine ester and its derivatives, dioxane and its derivatives, rofenine and its derivatives, and peroxazone and its derivatives.

[0114] In optional embodiments, the nanoparticle-based markers include, but are not limited to, nanoparticles, colloids, organic nanoparticles, magnetic nanoparticles, quantum dot nanoparticles, and rare earth complex nanoparticles.

[0115] In optional embodiments, the colloid includes, but is not limited to, colloidal metals, dispersed dyes, dye-labeled microspheres, and latexes.

[0116] In optional embodiments, the colloidal metal includes, but is not limited to, colloidal gold, colloidal silver, and colloidal selenium.

[0117] In an optional embodiment, the colloidal metal is colloidal gold.

[0118] In an optional embodiment, the antibody conjugate further includes a solid-phase carrier conjugated to the anti-κ light chain antibody or its antigen-binding fragment.

[0119] In an optional embodiment, the solid support is selected from microspheres, plates, and membranes.

[0120] In optional embodiments, the solid support includes, but is not limited to, magnetic microspheres, plastic microspheres, plastic microparticles, microporous plates, glass, capillaries, nylon, and nitrocellulose membranes.

[0121] In an optional embodiment, the plastic microparticles are nanospheres, such as latex.

[0122] In a sixth aspect, the present invention provides a reagent or kit comprising the above-described anti-κ light chain antibody or its antigen-binding fragment or the above-described antibody conjugate.

[0123] As previously stated, the anti-κ light chain antibody or its antigen-binding fragment in some embodiments or examples of the present invention can effectively bind to κ light chains. Therefore, reagents or kits containing the anti-κ light chain antibody or its antigen-binding fragment can effectively perform qualitative or quantitative detection of κ light chains. The reagents or kits provided by the present invention can be used, for example, for detections involving the specific binding properties of κ light chains and their antibodies, such as immunoblotting and immunoprecipitation. As previously stated, the anti-κ light chain antibody or its antigen-binding fragment in some embodiments or examples of the present invention has higher binding activity or affinity to κ light chains. Therefore, reagents or kits containing the anti-κ light chain antibody or its antigen-binding fragment have higher detection sensitivity or specificity.

[0124] In a seventh aspect, the present invention provides a method for detecting κ-type light chains, comprising: a) contacting the above-mentioned anti-κ-type light chain antibody or its antigen-binding fragment, antibody conjugate, reagent or kit with κ-type light chains in a sample to be tested under conditions sufficient to cause an antibody / antigen binding reaction to form an immune complex; and b) detecting the presence of the immune complex, the presence of the complex indicating the presence of the antigen in the test sample;

[0125] In an optional embodiment, the immune complex further includes a second antibody that binds to the anti-κ light chain antibody or its antigen-binding fragment.

[0126] In an optional embodiment, the immune complex further includes a second antibody that binds to a κ-type light chain.

[0127] Eighthly, the present invention provides a nucleic acid molecule encoding the above-mentioned anti-κ light chain antibody or its antigen-binding fragment.

[0128] In a ninth aspect, the present invention provides a carrier containing the above-mentioned nucleic acid molecules.

[0129] In a tenth aspect, the present invention provides cells containing the above-described carrier.

[0130] In one aspect, the present invention provides a method for preparing anti-κ light chain antibodies or antigen-binding fragments thereof, comprising: culturing cells as described above.

[0131] In a twelfth aspect, the present invention provides the use of the above-described anti-κ light chain antibody or its antigen-binding fragment, antibody conjugate, or the above-described reagent or kit in the preparation of products for detecting κ light chains.

[0132] In a thirteenth aspect, the present invention provides the use of the above-described antibody or its antigen-binding fragment, antibody conjugate, or the above-described reagent or kit in detecting κ-type light chains or indicating κ-type light chain-related diseases.

[0133] In a fourteenth aspect, the present invention provides a method for indicating a subject's κ-type light chain-related disease, comprising:

[0134] a) Under conditions sufficient to induce antibody / antigen binding, the antibody or its antigen-binding fragment, antibody conjugate, or the reagent or kit described above is contacted with a κ-type light chain in a sample from a subject to form an immune complex; and

[0135] b) Detect the presence of the immune complex, the presence of which indicates the presence or status of the subject's κ-type light chain-related disease.

[0136] In an optional embodiment, the immune complex further includes a second antibody that binds to the antibody or its antigen-binding fragment.

[0137] In an optional embodiment, the immune complex further includes a second antibody that binds to a κ-type light chain.

[0138] In an optional implementation, the κ-type light chain-related diseases described in aspect thirteen or fourteen are selected from diseases such as multiple myeloma, macroproteinemia, connective tissue diseases, infections, acute and chronic hepatitis, cirrhosis, nephropathy, and diabetes.

[0139] Based on the amino acid sequence of the anti-κ light chain antibody or its antigen-binding fragment disclosed in this invention, those skilled in the art will readily conceive of using genetic engineering or other techniques (chemical synthesis, recombinant expression) to prepare the anti-κ light chain antibody or its antigen-binding fragment. For example, the anti-κ light chain antibody or its antigen-binding fragment can be isolated and purified from the culture product of recombinant cells capable of recombinantly expressing the anti-κ light chain antibody or its antigen-binding fragment as described in any of the preceding claims. This is easily achievable by those skilled in the art. Therefore, regardless of the technique used to prepare the anti-κ light chain antibody or its antigen-binding fragment of this invention, it falls within the protection scope of this invention.

[0140] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0141] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. While any methods and materials similar to or equivalent to those described herein may be used in the practice or testing of formulations or unit doses herein, some methods and materials are described hereby. Unless otherwise stated, the techniques employed or considered herein are standard methods. Materials, methods, and examples are illustrative and not limiting in nature.

[0142] Unless otherwise specified, the practice of this invention will employ conventional techniques of cell biology, molecular biology (including recombinant technologies), microbiology, biochemistry, and immunology, which are within the capabilities of those skilled in the art. This technique is well explained in the literature, such as *Molecular Cloning: A Laboratory Manual*, 2nd edition (Sambrook et al., 1989); *Oligonucleotide Synthesis* (edited by M.J. Gait, 1984); *Animal Cell Culture* (edited by R.R. Freshney, 1987); *Methods in Enzymology* (Academic Press, Inc.); *Handbook of Experimental Immunology* (edited by D.M. Weir and C.C. Blackwell); *Gene Transfer Vectors for Mammalian Cells* (edited by J.M. Miller and M.P. Calos, 1987); *Current Protocols in Molecular Biology* (edited by F.M. Mausubel et al., 1987); and *PCR: The Polymerase Chain Reaction*. The references cited in the references are: "Reaction" (Mullis et al., ed., 1994); and "Current Protocols in Immunology" (JEColigan et al., ed., 1991), each of which is explicitly incorporated herein by reference.

[0143] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0144] Example 1: Preparation of Anti-KAPPA 12G3 Monoclonal Antibody

[0145] In this embodiment, restriction endonucleases and Prime Star DNA polymerase were purchased from Takara. The MagExtractor RNA extraction kit was purchased from TOYOBO. BD SMART TM The RACE cDNA Amplification Kit was purchased from Takara. The pMD-18T vector was purchased from Takara. The plasmid extraction kit was purchased from Tiangen Biotech. Primer synthesis and gene sequencing were performed by Invitrogen. The hybridoma cell line secreting the Anti-KAPPA 12G3 monoclonal antibody was a hybridoma cell line prepared in our laboratory and was revived for later use.

[0146] (1) Antibody gene preparation

[0147] mRNA was extracted from hybridoma cell lines secreting Anti-KAPPA12G3 monoclonal antibody, and DNA products were obtained by RT-PCR. The product was then inserted into the pMD-18T vector after an A-addition reaction with rTaq DNA polymerase. The vector was then transformed into DH5α competent cells. After bacterial growth, four clones of the Heavy Chain and Light Chain genes were collected and sent to a gene sequencing company for sequencing.

[0148] (2) Sequence analysis of the variable region gene of Anti-KAPPA12G3 antibody

[0149] The gene sequences obtained from the sequencing were analyzed in the Kabat antibody database and VNTI11.5 software was used to confirm that the genes amplified by both heavy and light chain primer pairs were correct. Among the gene fragments amplified by the Light Chain primer pair, the VL gene sequence was 321 bp, with a 57 bp leader peptide sequence preceding it; among the gene fragments amplified by the Heavy Chain primer pair, the VH gene sequence was 354 bp, belonging to the VH1 gene family, with a 57 bp leader peptide sequence preceding it.

[0150] (3) Construction of recombinant antibody expression plasmid

[0151] pcDNA TM 3.4 The vector is a constructed recombinant antibody eukaryotic expression vector. This expression vector has been introduced with multiple cloning restriction sites such as HindIII, BamHI, and EcoRI, and is named pcDNA3.4A expression vector, hereinafter referred to as 3.4A expression vector. Based on the sequencing results of the variable region gene of the antibody in pMD-18T, VL and VH gene-specific primers of this antibody were designed, with HindIII and EcoRI restriction sites and protective bases at both ends, respectively. The 0.70kb Light Chain gene fragment and the 1.38kb Heavy Chain gene fragment were amplified by PCR.

[0152] The Heavy Chain and Light Chain gene fragments were digested with HindIII / EcoRI, and the 3.4A vector was also digested with HindIII / EcoRI. After purification and recovery of the fragments and vector, the Heavy Chain gene and Light Chain gene were ligated into the 3.4A expression vector to obtain recombinant expression plasmids of Heavy Chain and Light Chain, respectively.

[0153] 2. Recombinant antibody production

[0154] HEK293 cells were revived early and passaged to a 200ml volume to achieve a cell density of 3–5 × 10⁻⁶ cells / mL. 6 Cell density reached the required antibody concentration and cell viability >95%; cells were washed by centrifugation, reconstituted with culture medium, and the cell density was adjusted to 2.9 × 10⁻⁶ cells / ml. 6 Cells were washed at a concentration of cells / ml and reconstituted with culture medium, which served as a cell dilution buffer. Plasmid DNA and transfection reagent dilution buffers were prepared separately using culture medium. The transfection reagent dilution buffer was added to the plasmid DNA dilution buffer, mixed well, and incubated at room temperature for 15 min. This mixture was then slowly added to the cell dilution buffer over 1 min, mixed well, and samples were taken for cell counting. Cell viability after transfection was recorded and observed. The cells were then incubated at 35°C with a rotation speed of 120 rpm and a CO2 concentration of 8%. After 13 days, the samples were centrifuged and collected. The supernatant was purified using a protein A affinity chromatography column. 6 μg of the purified antibody was subjected to reducing SDS-PAGE, as shown in the figure. The reducing SDS-PAGE showed two bands: one with a Mr of 50 kDa (heavy chain) and the other with a Mr of 28 kDa (light chain).

[0155] The resulting antibody was named Anti-KAPPA 12G3Rmb1. Mutations were performed on Anti-KAPPA 12G3Rmb1 to obtain a mutant antibody. The heavy chain (H) and light chain (L) sequences of the above antibody are shown in the table below:

[0156] Table 2 Antibody Sequences

[0157] Antibody name Heavy chain Light chain Anti-KAPPA12G3Rmb1 SEQ ID NO:22 SEQ ID NO:27 Anti-KAPPA12G3Rmb2 SEQ ID NO:22 SEQ ID NO:28 Anti-KAPPA12G3Rmb3 SEQ ID NO:22 SEQ ID NO:29 Anti-KAPPA 12G3Rmb4 SEQ ID NO:23 SEQ ID NO:27 Anti-KAPPA12G3Rmb5 SEQ ID NO:23 SEQ ID NO:28 Anti-KAPPA12G3Rmb6 SEQ ID NO:23 SEQ ID NO:29

[0158] Example 2: Antibody Performance Detection

[0159] 1. Affinity Analysis

[0160] The antibody was pre-diluted and purified, and the KAPPA antigen (purchased from Biospacific, catalog number J82700478) was serially diluted. Using a CM5 chip pre-coupled with goat anti-mouse IgG, the binding and dissociation curves of the antigen and antibody were tested on a Biacore 8K+ instrument. The instrument automatically fitted and obtained the affinity constant, binding rate, and dissociation rate. The results showed that the affinity of antibodies Anti-KAPPA12G3Rmb1 to Anti-KAPPA 12G3Rmb6 for KAPPA antigen was 1.0 × 10⁻⁶. -12 M≤KD<1.0×10 - 7 M, and it has a better affinity for the control antibody and KAPPA antigen. (KD represents the equilibrium dissociation constant, i.e., the affinity constant; ka represents the binding rate; kd represents the dissociation rate)

[0161] 2. Activity identification

[0162] Dilute KAPPA antigen (purchased from Biospacific, catalog number J82700478) to 2 μg / ml with coating buffer (mainly NaHCO3), 100 μL per well, and incubate overnight at 4°C. The next day, wash twice with washing buffer (mainly Na2HPO4 + NaCl), and blot dry. Add blocking buffer (20% BSA + 80% PBS), 120 μL per well, incubate at 37°C for 1 hour, and blot dry. Add diluted purified antigen. In vivo and control antibodies, 100 μL / well, 37℃, 30 min; wash 5 times with washing buffer, pat dry; add goat anti-mouse IgG-HRP, 100 μL / well, 37℃, 30 min; wash 5 times with washing buffer, pat dry; add chromogenic solution A (50 μL / well), add chromogenic solution B (50 μL / well), 10 min; add stop solution, 50 μL / well; read OD value at 450 nm (reference 630 nm) on the microplate reader.

[0163] Notes: Solution A (main components: citric acid + sodium acetate + acetanilide + urea peroxide); Solution B (main components: citric acid + EDTA·2Na + TMB + concentrated HCl); Stop solution (EDTA·2Na + concentrated H2SO4)

[0164] Table 3 Activity Data

[0165] Concentration (ng / ml) 125.00 62.50 31.25 15.63 7.81 0.00 Comparison 1.268 0.734 0.419 0.255 0.101 0.025 Anti-KAPPA 12G3Rmb1 1.996 1.439 0.814 0.464 0.282 0.032 Anti-KAPPA 12G3Rmb2 1.956 1.422 0.825 0.427 0.254 0.032 Anti-KAPPA 12G3Rmb3 1.936 1.437 0.836 0.443 0.236 0.036 Anti-KAPPA 12G3Rmb4 1.947 1.433 0.841 0.457 0.228 0.034 Anti-KAPPA12G3Rmb5 1.861 1.116 0.604 0.367 0.207 0.075 Anti-KAPPA12G3Rmb6 1.938 1.172 0.646 0.373 0.218 0.092

[0166] 3. Stability assessment

[0167] The above-mentioned antibodies were placed at 4℃ (refrigerator), -80℃ (refrigerator), and 37℃ (incubator) for 21 days. Samples were taken at 7, 14, and 21 days for observation of their state, and the activity of the 21-day sample was tested. The results showed that no significant changes in protein state were observed under the three testing conditions after 21 days, and the activity did not decrease with increasing testing temperature, indicating that the above-mentioned antibodies were stable. Table 4 below shows the OD results of enzyme immunoassay for Anti-KAPPA 12G3Rmb3 antibody after 21 days of testing.

[0168] Table 4 Stability Data

[0169] Sample concentration (ng / ml) 62.50 31.25 0.00 4℃, 21-day sample 1.447 0.836 0.027 -80℃, 21-day sample 1.452 0.845 0.026 37℃, 21-day sample 1.426 0.823 0.025

[0170] 4. Actual testing performance analysis

[0171] The antibody Anti-KAPPA 12G3Rmb1 to Anti-KAPPA 12G3Rmb6 was paired with another antibody and used on a biochemical platform to analyze the antibody's performance in actual detection.

[0172] The detection procedure includes: aspirating 1.5 μL of sample from the sample tray and simultaneously aspirating 200 μL of R1 (Tris buffer) into a cuvette, mechanically stirring, and incubating at 37°C for 5 minutes; adding 50 μL of R2 (antibody-conjugated latex reagent) into the cuvette and mechanically stirring; detecting at a wavelength of 570 nm, and recording the absorbance values ​​at 7 minutes and 30 seconds and 12 minutes from the time the sample was added. The difference between these values ​​is the reactivity of the sample. The reactivity is directly proportional to the concentration of Kappa FLC in the sample. Specific reactivity data are shown in Table 5 below.

[0173] Table 5 Biochemical Detection Reactivity Data

[0174]

[0175] Note: The blank calibrator column refers to the background value detected when there is no sample, while the reaction data obtained at other calibrator concentrations are the reaction rate data after subtracting the background value.

[0176] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0177] The partial amino acid sequences involved in this application are shown in Table 6:

[0178] Table 6 Amino acid sequence list

[0179]

[0180]

Claims

1. An anti-κ light chain antibody or its antigen-binding fragment, characterized in that, The anti-κ light chain antibody or its antigen-binding fragment comprises three complementarity-determining regions of the heavy chain variable region as shown in any of SEQ ID NO:20 or 21, and three complementarity-determining regions of the light chain variable region as shown in any of SEQ ID NO:24, 25, or 26; the complementarity-determining regions of the variable region are defined by any one of the Kabat, Chothia, IMGT, AbM, or Contact systems.

2. An anti-κ light chain antibody or its antigen-binding fragment, characterized in that, The anti-κ light chain antibody or its antigen-binding fragment includes the following complementarity-determining region: HCDR1, its amino acid sequence is shown in SEQ ID NO:

1. HCDR2, its amino acid sequence is shown in SEQ ID NO:

2. HCDR3, its amino acid sequence is shown in SEQ ID NO:

3. LCDR1, whose amino acid sequence is shown in SEQ ID NO:

4. LCDR2, whose amino acid sequence is shown in SEQ ID NO:5, and LCDR3, whose amino acid sequence is shown in either SEQ ID NO:6 or 18; or HCDR1, its amino acid sequence is shown in SEQ ID NO:

1. HCDR2, its amino acid sequence is shown in SEQ ID NO:

2. HCDR3, its amino acid sequence is shown in SEQ ID NO:

3. LCDR1, whose amino acid sequence is shown in SEQ ID NO:

17. LCDR2, whose amino acid sequence is shown in SEQ ID NO:5, and LCDR3, whose amino acid sequence is shown in SEQ ID NO:

6.

3. The anti-κ light chain antibody or its antigen-binding fragment according to claim 1 or 2, characterized in that, The anti-κ light chain antibody or its antigen-binding fragment also has HFR1, HFR2, HFR3, HFR4, LFR1, LFR2, LFR3 and LFR4.

4. The anti-κ light chain antibody or its antigen-binding fragment according to claim 3, characterized in that, The HFR1 comprises SEQ ID NO:7 or an amino acid sequence having at least 80% identity with it; The HFR2 comprises SEQ ID NO:8 or an amino acid sequence having at least 80% identity with it; The HFR3 comprises SEQ ID NO:9 or an amino acid sequence having at least 80% identity with it; The HFR4 comprises SEQ ID NO:10 or an amino acid sequence having at least 80% identity with it; The LFR1 includes SEQ ID NO:11 or an amino acid sequence having at least 80% identity with it; The LFR2 comprises SEQ ID NO:12 or an amino acid sequence having at least 80% identity with it; The LFR3 includes SEQ ID NO:13 or an amino acid sequence having at least 80% identity with it; The LFR4 includes SEQ ID NO:14 or an amino acid sequence that is at least 80% identical to it.

5. An anti-κ light chain antibody or its antigen-binding fragment, comprising a heavy chain variable region and a light chain variable region, characterized in that, The amino acid sequence of the heavy chain variable region is shown in SEQ ID NO:20; the amino acid sequence of the light chain variable region is shown in any one of SEQ ID NO:24, 25, or 26; or The amino acid sequence of the heavy chain variable region is shown in SEQ ID NO:21; the amino acid sequence of the light chain variable region is shown in any one of SEQ ID NO:24, 25, and 26.

6. The anti-κ light chain antibody or its antigen-binding fragment according to any one of claims 1, 2, 4, and 5, characterized in that, The anti-κ light chain antibody or its antigen-binding fragment further includes a constant region.

7. The anti-κ light chain antibody or its antigen-binding fragment according to claim 6, characterized in that, The constant region includes the heavy chain constant region and / or the light chain constant region.

8. The anti-κ light chain antibody or its antigen-binding fragment according to claim 7, characterized in that, The heavy chain constant region is selected from any one of the heavy chain constant regions of IgG, IgA, IgM, IgE, and IgD, or a combination of multiple constant region segments.

9. The anti-κ light chain antibody or its antigen-binding fragment according to claim 7, characterized in that, The heavy chain constant region includes CH1 of IgG, the hinge region of IgG, CH2 of IgM, CH3 of IgM, and / or CH4 of IgM.

10. The anti-κ light chain antibody or its antigen-binding fragment according to claim 6, characterized in that, The species source of the constant region is cattle, horses, pigs, sheep, goats, rats, mice, dogs, cats, rabbits, donkeys, deer, mink, chickens, ducks, geese, or humans.

11. The anti-κ light chain antibody or its antigen-binding fragment according to claim 6, characterized in that, The species source of the constant region is mice.

12. The anti-κ light chain antibody or its antigen-binding fragment according to claim 7, characterized in that, The heavy chain constant region sequence is as shown in SEQ ID NO:15 or has at least 80% identity with it.

13. The anti-κ light chain antibody or its antigen-binding fragment according to claim 7, characterized in that, The light chain constant region sequence is as shown in SEQ ID NO:16 or has at least 80% identity with it.

14. The antibody or antigen-binding fragment thereof according to any one of claims 1, 2, 4, and 5, characterized in that, The antigen-binding fragment is selected from any one of the antibody's F(ab')2, Fab', Fab, Fv, and scFv.

15. An anti-κ light chain antibody or an antigen-binding fragment thereof, said antibody comprising a heavy chain and a light chain, characterized in that, The amino acid sequence of the heavy chain is shown in SEQ ID NO:22; the amino acid sequence of the light chain is shown in any one of SEQ ID NO:27, 28, or 29; or The amino acid sequence of the heavy chain is shown in SEQ ID NO:23; the amino acid sequence of the light chain is shown in any one of SEQ ID NO:27, 28, and 29.

16. An antibody conjugate, characterized in that, The antibody conjugate comprises the anti-κ light chain antibody or its antigen-binding fragment as described in any one of claims 1 to 15 and biotin conjugated to the anti-κ light chain antibody or its antigen-binding fragment.

17. An antibody conjugate, characterized in that, The antibody conjugate comprises an anti-κ light chain antibody or its antigen-binding fragment as described in any one of claims 1 to 15, and a label or solid-phase carrier conjugated to the anti-κ light chain antibody or its antigen-binding fragment.

18. The antibody conjugate according to claim 17, characterized in that, The markers are selected from fluorescent dyes, enzymes, radioactive isotopes, chemiluminescent reagents, and nanoparticle markers.

19. The antibody conjugate according to claim 17, characterized in that, The solid support is selected from microspheres.

20. A reagent or kit, characterized in that, The reagent or kit comprises an anti-κ light chain antibody or its antigen-binding fragment as described in any one of claims 1 to 15, or an antibody conjugate as described in any one of claims 16 to 19.

21. Use of the anti-κ light chain antibody or antigen-binding fragment thereof according to any one of claims 1 to 15, the antibody conjugate according to any one of claims 16 to 19, or the reagent or kit according to claim 20 in the preparation of products for detecting κ light chains.

22. The use according to claim 21, characterized in that, include: a) Under conditions sufficient to induce an antibody / antigen binding reaction, the anti-κ light chain antibody or its antigen-binding fragment according to any one of claims 1 to 15, the antibody conjugate according to any one of claims 16 to 19, or the reagent or kit according to claim 20 is brought into contact with the κ light chain in the sample to be tested to form an immune complex. and b) Detect the presence of the immune complex, the presence of which indicates the presence of the antigen in the sample to be tested.

23. The use according to claim 22, characterized in that, The immune complex further includes a second antibody, which binds to the anti-κ light chain antibody or its antigen-binding fragment.

24. The use according to claim 22, characterized in that, The immune complex also includes a second antibody that binds to a κ-type light chain.

25. A nucleic acid, characterized in that, It encodes the anti-κ light chain antibody or its antigen-binding fragment as described in any one of claims 1 to 15.

26. A carrier, characterized in that, It contains the nucleic acid as described in claim 25.

27. A cell characterized in that, It contains the nucleic acid as described in claim 25 or the vector as described in claim 26.

28. A method for preparing the anti-κ light chain antibody or its antigen-binding fragment according to any one of claims 1 to 15, characterized in that, It includes: Culture the cells as described in claim 27.

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