Antibodies or functional fragments thereof against rf and uses thereof

Abstract

The present application relates to the field of biotechnology, in particular to an antibody or a functional fragment thereof against RF and application thereof, the antibody sequence disclosed in the present application is stable in performance, and can specifically combine with RF in the presence of endogenous interference substances, has affinity to HAMAs, can simultaneously reduce or eliminate the interference of RF and HAMAs on antigen-antibody detection, and is of great significance for obtaining correct clinical diagnosis results.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology, specifically relating to anti-RF antibodies or their functional fragments and their applications.

[0002] This invention claims priority to application No. 202311056555.3, filed on August 22, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0003] With the rapid technological advancements of domestic in vitro diagnostic reagent manufacturers, the development of in vitro diagnostic reagent kits in China is increasing. Immunodiagnosis has become a mainstream diagnostic technology. The most crucial factor in producing highly sensitive and specific reagents is selecting antibodies or antigens with highly specific binding to target molecules. However, in actual immunoassays, patient samples contain various endogenous interfering substances, such as rheumatoid factor (RF), heterophile antibodies (Id), human anti-animal antibodies (HAAA), and drugs and their metabolites. These endogenous interfering substances can lead to false positives or false negatives in diagnosis. Therefore, improving reagents and correctly blocking endogenous interfering substances is essential to obtaining accurate clinical results from diagnostic reagents.

[0004] Blockers are a class of materials used in the development of in vitro diagnostic reagents to reduce the influence of endogenous interfering substances from patient samples. Blockers are divided into passive blockers and active blockers. Passive blockers involve adding heterologous animal IgG, which competitively binds to interfering antibodies. Active blockers involve adding a component that specifically, actively, and efficiently neutralizes interfering antibodies, thereby blocking unintended binding. Market feedback indicates that passive blockers are used in large quantities, but their effectiveness is not significant. Considering current market demand, active blockers are the preferred choice.

[0005] Rheumatoid factor (RF) is an antibody produced in the body in response to infectious agents (bacteria, viruses, etc.), using denatured IgG as the antigen; hence, it is also called an anti-antibody. Common types of rheumatoid factor include IgM, IgG, IgA, and IgE. Rheumatoid factor is ubiquitous in the human body and plays a certain physiological role. It is mainly found in the serum and synovial fluid of patients with rheumatoid arthritis, primarily in the IgM form. Human anti-mouse antibodies (HAMAs) are among the most challenging anti-animal antibodies for immunological detection and have received the most attention to date, largely due to the widespread use of monoclonal antibody drugs. HAMAs are anti-antibodies, including IgG, IgM, IgA, and a small amount of IgE. They include idiotype antibodies, allotype antibodies, and anti-anti-idiotype antibodies. Idiotype antibodies can bind to the Fab fragment of immunoglobulins. 80% of HAMAs are anti-idiotype antibodies. Preparing active blocking agents to block the effects of endogenous interfering substances such as rheumatoid factor (RF) and human anti-mouse antibodies (HAMAs) on immunoassay reagents has become a key to improving the performance of reagent products. Summary of the Invention

[0006] This invention provides an anti-RF antibody or its functional fragment that can specifically bind to RF and also has affinity for HAMAs, thereby simultaneously reducing or eliminating the interference of RF and HAMAs on antigen-antibody detection.

[0007] Specifically as follows:

[0008] Anti-RF antibodies or their functional fragments and their applications, including HCDR1, HCDR2, HCDR3 and LCDR1, LCDR2, LCDR3, characterized in that HCDR1 to HCDR3 are amino acid sequences consistent with HCDR1 to HCDR3 in the heavy chain variable region shown in SEQ ID NO:1, and LCDR1 to LCDR3 are amino acid sequences consistent with LCDR1 to LCDR3 in the light chain variable region shown in SEQ ID NO:2.

[0009] Preferably, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by a Kabat, Chothia, IMGT, AbM, or Contact system.

[0010] Preferably, the antibody or its functional fragment is characterized in that HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are defined by the Kabat system.

[0011] The HCDR1 is shown in SEQ ID NO:3;

[0012] The HCDR2 is shown in SEQ ID NO:4;

[0013] The HCDR3 is shown in SEQ ID NO:5;

[0014] The LCDR1 is shown in SEQ ID NO:6;

[0015] The LCDR2 is shown in SEQ ID NO:7;

[0016] And the LCDR3 is as shown in SEQ ID NO:8.

[0017] In this paper, the terms "variable region" or "CDR" refer to the highly variable region of the heavy and light chains of an immunoglobulin, which contains one or more or even all of the major amino acid residues that contribute to the binding affinity of an antibody or antigen-binding fragment to the antigen or epitope it recognizes.

[0018] In this document, heavy chain variable regions (heavy chain complementarity-determining regions) are denoted by "HCDR," which includes HCDR1, HCDR2, and HCDR3; light chain complementarity-determining regions are denoted by "LCDR," which includes LCDR1, LCDR2, and LCDR3. Commonly used CDR labeling methods in the art include the Kabat numbering scheme, the IMGT numbering scheme, the Chothia and Lesk numbering scheme, and the new standardized numbering system introduced by Lefranc et al. in 1997 for all protein sequences of the immunoglobulin superfamily. Kabat et al. were the first to propose a standardized numbering scheme for immunoglobulin variable regions. Over the past few decades, the accumulation of sequences has led to the creation of the Kabat database, and the Kabat numbering scheme is generally considered the widely adopted standard for numbering antibody residues. This disclosure uses the Kabat annotation standard to label CDR regions, but CDR regions labeled by other methods are also within the scope of this invention.

[0019] In this article, the "backbone region" or "FR" region includes the heavy chain backbone region and the light chain backbone region, which refers to the region in the antibody heavy chain variable region (which can be represented as VH) and light chain variable region (which can be represented as VL) excluding the CDR. The heavy chain backbone region is represented by "HFR" and can be further subdivided into adjacent regions separated by CDR, including the HFR1, HFR2, HFR3 and HFR4 backbone regions; the light chain backbone region is represented by "LFR" and can be further subdivided into adjacent regions separated by CDR, including the LFR1, LFR2, LFR3 and LFR4 backbone regions.

[0020] Preferably, the antibody or its functional fragment further comprises the backbone regions HFR1, HFR2, HFR3, and HFR4 of the heavy chain variable region, and the backbone regions LFR1, LFR2, LFR3, and LFR4 of the light chain variable region.

[0021] Wherein, HFR1 is an amino acid sequence as shown in EQ ID NO:9 or an amino acid sequence having at least 80% homology with it;

[0022] The HFR2 is an amino acid sequence as shown in EQ ID NO:10 or an amino acid sequence having at least 80% homology with it;

[0023] The HFR3 is an amino acid sequence as shown in EQ ID NO:11 or an amino acid sequence having at least 80% homology with it;

[0024] The HFR4 is an amino acid sequence as shown in EQ ID NO:12 or an amino acid sequence having at least 80% homology with it;

[0025] The LFR1 is an amino acid sequence as shown in EQ ID NO:13 or an amino acid sequence having at least 80% homology with it;

[0026] The LFR2 is an amino acid sequence as shown in EQ ID NO:14 or an amino acid sequence that is at least 80% homologous to it;

[0027] The LFR3 is an amino acid sequence as shown in EQ ID NO:15 or an amino acid sequence having at least 80% homology with it;

[0028] The LFR4 is an amino acid sequence as shown in EQ ID NO:16 or an amino acid sequence that has at least 80% homology with it.

[0029] In this paper, the variable region of the heavy chain is obtained by connecting the following CDRs and FRs in the following combination: HFR1-HCDR1-HFR2-HCDR2-HFR3-HCDR3-HFR4; the variable region of the light chain is obtained by connecting the following CDRs and FRs in the following combination: LFR1-LCDR1-LFR2-LCDR2-LFR3-LCDR3-LFR4.

[0030] It should be noted that, in other embodiments, the amino acid sequences of each backbone region of the antibody or its functional fragment provided in this disclosure 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% homology with the corresponding backbone regions (SEQ ID NO: 9, 10, 11, 12, 13, 14, 15, or 16). In optional embodiments, the antibody or its functional fragment has a KD ≤ 10. -7 M, KD≤10 -8 M, KD≤10 -9 M, KD≤10 -10 M or KD≤10 -11 It has an affinity for human IgM.

[0031] Preferably, the antibody or its functional fragment further comprises a constant region;

[0032] Optionally, the constant region includes a heavy chain constant region and / or a light chain constant region;

[0033] Optionally, the heavy chain constant region is selected from the heavy chain constant regions of IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE or IgD; the light chain constant region is selected from the κ-type or λ-type light chain constant region.

[0034] Optionally, the species source of the constant region is cattle, horses, dairy cows, pigs, sheep, goats, rats, mice, dogs, cats, rabbits, camels, donkeys, deer, mink, chickens, ducks, geese, turkeys, fighting cocks, or humans;

[0035] Optionally, the species source of the constant region is mice;

[0036] Preferably, the functional fragment is selected from any one of the antibody's F(ab')2, Fab', Fab, Fv, and scFv.

[0037] The functional fragments of the aforementioned antibodies typically possess the same binding specificity as the antibodies from which they originate. Those skilled in the art will readily understand from the content of this disclosure that the functional 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 disclosure, those skilled in the art can readily obtain the aforementioned functional fragments. The functional fragments of the aforementioned antibodies can also be obtained using recombinant genetic techniques known to those skilled in the art or synthesized using, for example, automated peptide synthesizers, such as those sold by Applied BioSystems.

[0038] On the other hand, the present invention also discloses that the antibody conjugate comprises the antibody or a functional fragment thereof and a conjugated portion thereof;

[0039] Optionally, the coupling portion is selected from purified tags or detectable labels, such as colloidal gold, radioactive labels, luminescent substances, colored substances, enzymes such as fluorescent labels, chromophore labels, electron-dense labels such as radioactive isotopes, fluorophores, rhodamine and its derivatives, luciferase, luciferin, horseradish peroxidase, alkaline phosphatase, β-galactosidase, glucosylamylase, lysozyme, carbohydrate oxidase, glucose oxidase, galactose oxidase, and glucose-6-phosphate dehydrogenase, biotin / antibiotin protein, and one or more of spin labels;

[0040] Optionally, the coupling portion is selected from solid-phase carriers, such as magnetic microspheres, plastic microspheres, plastic microparticles, microporous plates, glass, capillaries, nylon and nitrocellulose membranes.

[0041] On the other hand, the present invention discloses a nucleic acid, characterized in that the nucleic acid encodes the antibody or a functional fragment thereof.

[0042] Nucleic acids are typically RNA or DNA, and nucleic acid molecules can be single-stranded or double-stranded. Nucleic acids are "effectively linked" when placed in a functional relationship with another nucleic acid sequence. For example, if a promoter or enhancer affects the transcription of a coding sequence, then the promoter or enhancer is effectively linked to said coding sequence. DNA nucleic acids are used when they are ligated into a vector.

[0043] Some embodiments of this disclosure also provide a carrier containing the aforementioned nucleic acid molecules.

[0044] Some embodiments of this disclosure also provide cells containing the above-described carrier.

[0045] Some embodiments of this disclosure also provide a method for preparing an antibody or a functional fragment thereof, comprising: culturing cells as described above, and separating and purifying the antibody or a functional fragment thereof from the culture product.

[0046] Based on the amino acid sequence of the antibody or its functional fragment in this disclosure, those skilled in the art will readily conceive of using genetic engineering or other techniques (chemical synthesis, recombinant expression) to prepare the antibody or its functional fragment, for example, by isolating and purifying the antibody or its functional fragment from the culture product of a recombinant cell capable of recombinantly expressing the antibody or its functional 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 antibody or its functional fragment of this disclosure, it falls within the protection scope of this disclosure.

[0047] On the other hand, the present invention discloses the use of the antibody or its functional fragment in the preparation of an immunoassay kit or in the preparation of an immunoblocker.

[0048] On the other hand, the present invention discloses an inhibitor comprising the antibody or a functional fragment thereof;

[0049] Optionally, the concentration of the antibody in the blocking agent is 5–100 μg / ml.

[0050] In an optional embodiment, the concentration of the antibody in the blocking agent is 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 μg / ml.

[0051] On the other hand, the present invention discloses a detection reagent or kit, the reagent or kit comprising the antibody or its functional fragment, the antibody-drug conjugate or the blocking agent.

[0052] In optional embodiments, the blocking agent included in the kit may be in the form of a liquid solution, attached to a solid support, or a dry powder. When the blocking agent is a liquid solution, the liquid solution may be an aqueous solution. When the immunoblocking agent is attached to a solid support, the preferred solid support may be a chromatography medium such as a membrane, test strip, plastic beads or plates, or a microscope slide. When the blocking agent is a dry powder, the powder can be reconstituted by adding a suitable solvent.

[0053] On the other hand, the present invention discloses a method for reducing / eliminating endogenous interference by adding the antibody or its functional fragment, the antibody-drug conjugate, or the blocking agent to an immune detection system.

[0054] On the other hand, the present invention discloses an immune detection method, the method comprising:

[0055] The antibody or its functional fragment, the antibody-drug conjugate, or the blocking agent is added to the immune detection system.

[0056] On the other hand, the present invention discloses a method for detecting RF, the method comprising:

[0057] A) Under conditions sufficient for a binding reaction to occur, the antibody or its functional fragment, the antibody-drug conjugate, the blocking agent, or the reagent or kit described herein is contacted with a sample from the subject to initiate a binding reaction; and

[0058] B) Detect the immune complexes produced by the binding reaction.

[0059] Beneficial effects

[0060] The antibody sequence disclosed in this invention has stable antibody performance and can specifically bind to RF in the presence of endogenous interfering substances. It also has affinity for HAMAs, which can simultaneously reduce or eliminate the interference of RF and HAMAs on antigen-antibody detection and obtain accurate clinical diagnostic results. Attached Figure Description

[0061] Figure 1 The antibody gel image disclosed in this invention shows the marker on the left and the purified antibody reduction band on the right.

[0062] Figure 2 The results of the experiment were obtained by detecting the interaction between the antibody and the recombinant expressed and purified human IgM using an enzyme-linked immunosorbent assay (ELISA). Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the examples or 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.

[0064] 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.

[0065] Unless otherwise specified, the practice of this disclosure 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., 2011), each of which is explicitly incorporated herein by reference.

[0066] Example 1: Preparation of mouse monoclonal antibodies against human endogenous interferon

[0067] 1. Immunogen preparation

[0068] First, ammonium sulfate is used to fractionate and precipitate human serum, based on the different solubilities of different proteins in a salt solution of a certain concentration, separating impurities and IgM antibodies. Then, molecular sieves are used to separate antibodies of different sizes based on the different pore sizes of the gel, separating different types of antibodies from the crude ammonium sulfate extract to obtain human IgM antibodies as immunogens.

[0069] 2. Mouse immunization and antibody detection

[0070] Five 6-8 week old SPF-grade female BALB / c mice were selected. Freund's complete adjuvant and human IgM at a concentration of 2 mg / ml were mixed in equal volumes and emulsified. The emulsified antigen was used to immunize the 6-8 week old SPF-grade female BALB / c mice, with each mouse receiving 40 μg of immunogen via paw injection. Two weeks after the initial immunization, the antigen protein was mixed with Freund's incomplete adjuvant and emulsified, and 40 μg of antigen protein was injected again into each mouse via paw injection or subcutaneous injection in the back. Two weeks later, blood was collected via tail vein, the supernatant was collected by centrifugation, and serum titer was detected by ELISA. Immunization was repeated every two weeks, and serum titer was measured. After two immunizations, the serum titer, after a million-fold dilution, was higher than 2.0. A serum titer of 10 was selected for screening. 6 Lymphocytes were isolated from the mice mentioned above for cell fusion.

[0071] C. Cell fusion and screening and subcloning of positive hybridoma cells

[0072] Antibody screening protocol is crucial for the successful development of the antibody of this invention. Lymphocytes from immunized mice were isolated and fused with cultured SP2 / 0 cells via PEG1500-mediated fusion or electrofusion. The fused cells were cultured in HAT-1640 medium containing 20% ​​FBS serum for screening. After one week, the medium was changed, and after another four days of culture, the culture supernatant was used for positive clone screening. Human IgM immunogen was used for screening positive wells. Wells with a high ELISA positive value to cell number ratio were selected for multiple subcloning. ELISA plates were coated with human IgM immunogen. The culture supernatant of the subclones was used to screen for monoclonal clones that showed affinity under antigen-coated conditions. The monoclonal hybridoma cell line with the highest affinity was selected, ultimately yielding a hybridoma cell line with a high antibody titer that secretes monoclonal antibodies against the human IgM immunogen, named Blocker-1.

[0073] 4. Production and purification of monoclonal antibodies

[0074] A group of 6-8 week old BALB / c mice were selected and injected intraperitoneally with 500 μL of paraffin oil to suppress the immune response. One week after injection, 0.5 ml of Blocker-1 hybridoma cells (approximately 1 × 10⁻⁶ cells) were injected intraperitoneally into the mice. 6 Quantity. Ascites fluid collection began two weeks later. The collected ascites fluid was purified by ammonium sulfate precipitation and protein G affinity purification to obtain the target antibody.

[0075] 5. Identification of monoclonal antibody subtypes and cloning of gene sequences

[0076] The heavy and light chain isotypes of monoclonal antibodies were identified using the Southern Biothech SBA Clonotyping System-HRP kit, following the manufacturer's instructions. The specific procedures were as follows:

[0077] 1. Dilute the capture antibody to 1 μg / mL with coating buffer (0.05 M pH 9.5 carbonate and bicarbonate buffer), add 100 μL / well to the microplate, and coat overnight at 4°C. Wash the plate three times with PBS buffer containing 0.05% Tween-20 (wash buffer).

[0078] 2. Dilute the culture supernatant of the hybridoma cells to be tested 1:1 with diluent (1% BSA, 0.1% PBST), add 100 μL / well to the ELISA plate, and incubate at 37°C for 30 minutes. Dilute the corresponding enzyme-labeled antibodies (Ig-HRP, IgG1-HRP, IgG2a-HRP, IgG2b-HRP, IgG3-HRP, IgM-HRP, kappa-HRP, lambda-HRP) 1:3000 with diluent.

[0079] 3. After washing the plate three times with washing buffer, add 100 μL of diluted enzyme-labeled antibody to each well and incubate at 37°C for 30 minutes. After washing three more times, add chromogenic buffer and incubate for approximately 5 minutes (depending on the reaction strength). Then, add 2M sulfuric acid to terminate the reaction and read the OD450 absorbance. The obtained murine monoclonal antibody against human endogenous interferon was identified as having an IgG1 heavy chain and a Kappa light chain. Based on the antibody subtype results, the antibody gene sequence was cloned using a RACE-based method. Hybridoma cells in good growth condition were collected, and total RNA was obtained from the hybridoma cells using a total RNA extraction kit. The mRNA was reverse transcribed into cDNA according to the Takara SMARTer RACE instructions, and the full-length sequence of the target antibody was amplified.

[0080] Example 2 Antibody Performance Verification

[0081] (1) Interaction between antibody and human IgM

[0082] This embodiment verifies the binding performance of the antibody of the present invention through the interaction between the antibody and human IgM.

[0083] The specific operating steps are as follows: Dilute the antibody to 1 μg / mL using coating buffer (0.05 M pH 9.5 carbonate and bicarbonate buffer) and coat it onto a standard 96-well ELISA plate. Modify the purified human IgM with biotinylation reagent (commercially available). Dilute the biotinylated human IgM to the target concentrations (0.3 ng / ml, 0.8 ng / ml, 2.5 ng / ml, ..., 200 ng / ml). Add 100 μl of the specific concentration of human IgM to each well coated with the target antibody and incubate at 37°C for 30 min. After washing the plate with washing buffer (150 mM NaCl solution containing 0.05% Tween-20), add 100 μl of a 1:5000 dilution of streptavidin-horseradish peroxidase conjugate (commercially available) to each well and incubate at 37°C for 15 min. Finally, the sample was incubated with ELISA colorimetric solution and the OD450 absorbance was detected using a microplate reader.

[0084] The results are shown in Table 1 and Figure 2 As shown, the results of the enzyme-linked immunosorbent assay (ELISA) were used to detect the interaction between the antibody and purified human IgM. The horizontal axis indicates the antibody concentration used, and the vertical axis indicates the ELISA result, specifically the absorbance value (OD450) detected by the spectrophotometer at 450 nm. A higher OD450 value indicates a stronger detected interaction. The results indicate a strong interaction between the antibody and human IgM, and the antibody of this invention is suitable for blocking endogenous interfering substances in humans.

[0085] Table 1. Results of linear experiments

[0086]

[0087]

[0088] Example 3: Application of Blocker-1 antibody in fPSA chemiluminescence detection kit

[0089] Blocker-1 antibody was prepared into a 20 μg / ml working solution using reagent R1. After thorough mixing, the reagent was placed into the R1 chamber of the reagent bottle. No Blocker-1 antibody was added to the blank group, while the control group received a 20 μg / ml working solution of control antibody prepared using reagent R1. Working solution R2 was placed into the R2 chamber of the reagent bottle, and magnetic bead working solution was placed into the magnetic bead chamber. The blocking effect of Blocker-1 antibody in the fPSA chemiluminescence assay kit on endogenous interference samples containing HAMAs and RF was tested using a fully automated chemiluminescence immunoassay analyzer, as shown in Table 2. Comparison with the blank and control groups revealed that Blocker-1 antibody had a significant blocking effect on clinical samples containing HAMAs and RF, and its performance was significantly superior to the control.

[0090] Table 2. Blocking results of chemiluminescence in clinical samples

[0091]

[0092]

[0093] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An antibody against IgM-type RF, characterized in that, It includes a heavy chain variable region and a light chain variable region. The heavy chain variable region includes HCDR1, HCDR2 and HCDR3, and the light chain variable region includes LCDR1, LCDR2 and LCDR3. The amino acid sequence of HCDR1 is shown in SEQ ID NO:3; The amino acid sequence of HCDR2 is shown in SEQ ID NO:4; The amino acid sequence of HCDR3 is shown in SEQ ID NO:5; The amino acid sequence of LCDR1 is shown in SEQ ID NO:6; The amino acid sequence of LCDR2 is shown in SEQ ID NO:7; The amino acid sequence of LCDR3 is shown in SEQ ID NO:

8.

2. The antibody according to claim 1, characterized in that, The antibody also includes the heavy chain variable region backbone regions HFR1, HFR2, HFR3 and HFR4, and the light chain variable region backbone regions LFR1, LFR2, LFR3 and LFR4; The HFR1 is an amino acid sequence as shown in SEQ ID NO:9 or an amino acid sequence having at least 80% homology with it; The HFR2 is an amino acid sequence as shown in SEQ ID NO:10 or an amino acid sequence having at least 80% homology with it; The HFR3 is an amino acid sequence as shown in SEQ ID NO:11 or an amino acid sequence having at least 80% homology with it; The HFR4 is an amino acid sequence as shown in SEQ ID NO:12 or an amino acid sequence having at least 80% homology with it; The LFR1 is an amino acid sequence as shown in SEQ ID NO:13 or an amino acid sequence having at least 80% homology with it; The LFR2 is an amino acid sequence as shown in SEQ ID NO:14 or an amino acid sequence having at least 80% homology with it; The LFR3 is an amino acid sequence as shown in SEQ ID NO:15 or an amino acid sequence having at least 80% homology with it; The LFR4 is an amino acid sequence as shown in SEQ ID NO:16 or an amino acid sequence having at least 80% homology with it.

3. The antibody according to claim 2, characterized in that, The antibody also contains a constant region.

4. The antibody according to claim 3, characterized in that, The constant region includes the heavy chain constant region and / or the light chain constant region.

5. The antibody according to claim 4, characterized in that, The heavy chain constant region is selected from the heavy chain constant regions of IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE or IgD; the light chain constant region is selected from the κ-type or λ-type light chain constant region.

6. The antibody according to claim 5, characterized in that, The species source of the constant region is cattle, horses, pigs, sheep, goats, rats, mice, dogs, cats, rabbits, camels, donkeys, deer, minks, chickens, ducks, geese, or humans.

7. The antibody according to claim 6, characterized in that, The species source of the constant region is mice.

8. An antibody conjugate, characterized in that, The antibody conjugate comprises the antibody as described in any one of claims 1 to 7 and a conjugated portion thereof, the conjugated portion being selected from a detectable label or solid-phase carrier.

9. The antibody conjugate according to claim 8, characterized in that, The detectable label is selected from one or more of colloidal gold, luminescent substances, electron-dense labels, or enzymes.

10. The antibody conjugate according to claim 9, characterized in that, The solid support is selected from one or more of magnetic microspheres, plastic microparticles, glass, and capillaries.

11. A blocking agent for IgM-type RF, characterized in that, The blocking agent includes the antibody according to any one of claims 1 to 7.

12. The blocking agent according to claim 11, characterized in that, The concentration of the antibody in the blocking agent is 5–100 μg / ml.

13. A detection reagent or kit, characterized in that, The reagent or kit comprises the antibody according to any one of claims 1 to 7, the antibody-drug conjugate according to any one of claims 8 to 10, or the blocking agent according to any one of claims 11 to 12.

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