Method and kit for detecting free light chain in sample

Abstract

The invention belongs to the technical field of in-vitro detection, and particularly relates to a method and a kit for detecting free light chains (FLC) in a sample. According to the kit for detecting or typing the free light chain in the sample and the detection method provided by the invention, the problem of carrying out accurate qualitative and typing on the low-abundance monoclonal FLC in the sample to be detected is solved; the detection method provided by the invention is higher in sensitivity, better in accuracy, simpler to operate and easier to realize automation, and does not have the subjectivity problem of manual interpretation; compared with other mass spectrometry methods, such as a liquid chromatography-tandem mass spectrometry method, the detection cost is lower, the operation is simpler, automation is easier to realize, the detection flux is higher, and popularization in clinical diagnosis and treatment is easier to realize.

Description

Technical Field

[0001] The present invention belongs to the field of in vitro detection technology, and specifically relates to a method and a kit for detecting free light chains in a sample. Background Art

[0002] Clinically, serum M protein is typically detected using serum protein electrophoresis (sPE) and serum immunofixation electrophoresis (sIFE). When these two techniques fail to meet the required sensitivity, serum free light chains (sFLC) are tested to avoid missing M protein. However, existing sFLC detection methods are mostly based on immunoturbidimetry, enzyme-linked immunosorbent assays, or chemiluminescence techniques. These methods quantify total kappa (κ) or total lambda (λ) light chains in human serum and indirectly determine the presence of monoclonal FLC by calculating the ratio of the two and comparing it to the clinical reference range. These methods are unable to directly analyze and detect monoclonal FLC. This indirect method may not accurately assess the presence of monoclonal FLC in patients with renal impairment, as serum FLC may be lost due to renal impairment, resulting in a ratio of κ to λ FLC within the normal clinical reference range. Furthermore, these indirect methods for detecting monoclonal FLC are currently only applicable to serum samples and are not suitable for urine FLC detection, which is also of great clinical significance.

[0003] Clinically, the detection of urine FLC is also performed through uIFE, in which the antibodies used are specific for FLC. Because uIFE first separates the protein in the urine through electrophoresis technology, and then uses specific antibodies to immunoprecipitate, fix and stain the electrophoretically separated proteins, manual analysis of the bands is used to determine whether monoclonal FLC is present in the urine. This method is based on the principle of electrophoresis and the protein content in urine is much lower than that in serum. Therefore, uIFE has poor sensitivity for detecting monoclonal FLC in urine. In addition, the manual interpretation of electrophoresis bands itself is highly subjective, and it is often impossible to give accurate test results for urine samples with low FLC content.

[0004] A urine FLC detection method with higher sensitivity and accuracy is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The present invention aims to solve, at least to a certain extent, one of the technical problems in the related art. To this end, one object of the present invention is to provide a kit and a detection method for detecting or typing free light chains in a sample. The present invention solves the problem of accurately characterizing and typing low-abundance monoclonal FLC in the sample to be tested. Compared with the uIFE method, the detection method provided by the present invention has higher sensitivity, better accuracy, simpler operation, and easier automation, and does not have the subjective problem of manual interpretation; compared with other mass spectrometry methods, such as liquid chromatography-tandem mass spectrometry, the detection cost is lower, the operation is simpler, it is easier to automate, the detection throughput is higher, and it is easier to promote in clinical diagnosis and treatment.

[0006] To this end, the first aspect of the present invention provides a kit for detecting or typing free light chains in a sample. According to an embodiment of the present invention, the kit comprises:

[0007] Antibody-bound magnetic beads;

[0008] elution solution;

[0009] Reaction buffer;

[0010] Wherein, the antibody is a κ-type and λ-type free light chain specific antibody,

[0011] The elution solution contains an antigen-antibody complex dissociation reagent,

[0012] The mass ratio of the antibody to the magnetic beads is 1:(10-1000),

[0013] The particle size of the magnetic beads is 0.5-5 μm.

[0014] By optimizing the reagents contained in the kit, the inventors obtained a kit for detecting or typing free light chains in samples. Using this kit, the problem of accurately qualitatively identifying and typing low-abundance monoclonal FLCs in the sample to be tested is solved. Compared with the uIFE method, the detection method provided by the present invention has higher sensitivity, better accuracy, simpler operation, and easier automation, and does not have the subjective problem of manual interpretation; compared with other mass spectrometry methods, such as liquid chromatography-tandem mass spectrometry, the detection cost is lower, the operation is simpler, it is easier to automate, and the detection throughput is higher, making it easier to promote in clinical diagnosis and treatment.

[0015] According to an embodiment of the present invention, the κ-type or λ-type free light chain specific antibody is a specific anti-human κ-type or λ-type free light chain antibody or a fragment thereof.

[0016] According to an embodiment of the present invention, the κ-type or λ-type free light chain-specific antibody is a monoclonal antibody or a polyclonal antibody or a fragment thereof.

[0017] According to an embodiment of the present invention, the κ-type and λ-type free light chain-specific antibodies are polyclonal antibodies.

[0018] According to an embodiment of the present invention, the affinity constant KD value of the κ-type and λ-type free light chain-specific antibodies is 100-100000 pM.

[0019] According to an embodiment of the present invention, in the kit, the ratio of the magnetic beads bonded to the κ-type free light chain-specific antibody to the magnetic beads bonded to the λ-type free light chain-specific antibody is (1-10):1.

[0020] According to an embodiment of the present invention, the surface of the magnetic beads is modified with proteins or chemical groups, and the proteins or chemical groups are used to bind to the antibodies.

[0021] According to an embodiment of the present invention, the chemical group includes at least one selected from amino, carboxyl, epoxy, and hydroxyl groups.

[0022] According to an embodiment of the present invention, the protein is streptavidin.

[0023] According to an embodiment of the present invention, when the surface of the magnetic beads is modified with streptavidin, the antibody is linked to biotin.

[0024] According to an embodiment of the present invention, the antigen-antibody complex dissociation reagent includes at least one selected from an organic acid solution, an inorganic acid solution, and an alkaline solution.

[0025] The organic acid solution comprises at least one selected from the group consisting of formic acid solution, acetic acid solution, trifluoroacetic acid solution, propionic acid solution, glycolic acid solution, amino acid solution, butyric acid solution, citric acid, succinic acid, ascorbic acid, lactic acid, malic acid, and tartaric acid;

[0026] The inorganic acid solution includes at least one selected from hydrochloric acid solution, sulfuric acid solution, and phosphoric acid solution;

[0027] The alkaline solution includes at least one selected from sodium hydroxide solution, potassium hydroxide solution, tris(hydroxymethyl)aminomethane solution, tetraethylammonium bromide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium bicarbonate solution, ammonia solution, and urea solution.

[0028] According to an embodiment of the present invention, the antigen-antibody complex dissociation reagent is a trifluoroacetic acid solution.

[0029] According to an embodiment of the present invention, the mass concentration of the trifluoroacetic acid solution is 0.05-5%.

[0030] According to a preferred embodiment of the present invention, the mass concentration of the trifluoroacetic acid solution is 0.1-5%.

[0031] According to an embodiment of the present invention, the reaction buffer comprises at least one selected from PBS, PBST, and TBST solutions.

[0032] According to an embodiment of the present invention, the reaction buffer is PBST solution.

[0033] According to an embodiment of the present invention, the kit further includes a cleaning solution.

[0034] According to an embodiment of the present invention, the cleaning solution includes at least one selected from PBS, PBST, and TBST solutions.

[0035] According to an embodiment of the present invention, the cleaning solution is PBST solution.

[0036] According to an embodiment of the present invention, the kit further comprises a matrix solution for MALDI-TOF MS detection.

[0037] According to an embodiment of the present invention, the matrix in the matrix liquid includes at least one selected from sinapinic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, anthracene triol, and 3-indole acrylic acid.

[0038] According to an embodiment of the present invention, the matrix in the matrix liquid is sinapinic acid.

[0039] A second aspect of the present invention provides a method for detecting free light chains in a sample. According to an embodiment of the present invention, the method comprises using the kit for detecting or typing free light chains in a sample described in the first aspect to detect the sample to be tested, thereby determining whether the sample to be tested contains free light chains, or typing the free light chains into κ or λ types.

[0040] A third aspect of the present invention provides a method for detecting free light chains in a sample. According to an embodiment of the present invention, the method comprises:

[0041] S1: contacting a sample to be tested and antibody-bound magnetic beads in a reaction buffer, so that the κ-type and / or λ-type free light chains contained in the sample to be tested specifically bind to the antibodies bound to the magnetic beads, thereby obtaining antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains;

[0042] S2: performing an elution treatment and a magnetic separation treatment on the antigen-antibody complex magnetic beads to elute and separate the enriched κ and / or λ free light chains from the antibody, thereby obtaining a test solution containing κ and / or λ free light chains;

[0043] S3: Spot the test solution on the sample chip, perform crystallization treatment, and use MALDI-TOF MS to detect whether the test sample contains free light chains, or perform κ type and λ type typing of the free light chains.

[0044] Wherein, the antibodies are κ-type and λ-type free light chain specific antibodies.

[0045] The present invention provides a new FLC detection method. Magnetic beads bonded with antibodies specific for κ- and λ-type FLCs are used to enrich the two types of FLCs in a test sample (e.g., urine). After elution, the two types of FLCs are detected by MALDI-TOF MS. Software automatically analyzes the results and determines the presence and specific type of monoclonal FLC in the test sample (e.g., urine). This method solves the problem of accurately characterizing and typing monoclonal FLCs in a test sample (e.g., urine). Compared to the uIFE method, the detection method provided by the present invention offers higher sensitivity, better accuracy, simpler operation, and greater automation potential, eliminating the subjectivity inherent in manual interpretation.

[0046] According to an embodiment of the present invention, in the antibody-bound magnetic beads, the mass ratio of the antibody to the magnetic beads is 1:(10-1000).

[0047] According to an embodiment of the present invention, the particle size of the magnetic beads is 0.5-5 μm.

[0048] According to an embodiment of the present invention, the surface of the magnetic beads is modified with proteins or chemical groups, and the proteins or chemical groups are used to bind to the antibodies.

[0049] According to an embodiment of the present invention, the chemical group includes at least one selected from amino, carboxyl, epoxy, and hydroxyl groups.

[0050] According to an embodiment of the present invention, the protein is streptavidin.

[0051] According to an embodiment of the present invention, when the surface of the magnetic beads is modified with streptavidin, the antibody is linked to biotin.

[0052] According to an embodiment of the present invention, the κ-type or λ-type free light chain specific antibody is a specific anti-human κ-type or λ-type free light chain antibody or a fragment thereof.

[0053] According to an embodiment of the present invention, the κ-type or λ-type free light chain-specific antibody is a monoclonal antibody or a polyclonal antibody or a fragment thereof.

[0054] According to an embodiment of the present invention, the κ-type and λ-type free light chain-specific antibodies are polyclonal antibodies.

[0055] According to an embodiment of the present invention, the affinity constant KD value of the κ-type and λ-type free light chain-specific antibodies is 100-100000 pM.

[0056] According to an embodiment of the present invention, the ratio of the magnetic beads bonded to the κ-type free light chain-specific antibody to the magnetic beads bonded to the λ-type free light chain-specific antibody is (1-10):1.

[0057] According to an embodiment of the present invention, the reaction buffer comprises at least one selected from PBS, PBST, and TBST solutions.

[0058] According to an embodiment of the present invention, the reaction buffer is PBST solution.

[0059] According to an embodiment of the present invention, in step S1 , when contacting, the volume ratio of the sample to be tested to the reaction buffer is 1:(1-200).

[0060] According to an embodiment of the present invention, in the reaction buffer, the mass concentration of the antibody-bound magnetic beads is 1-100 mg / mL.

[0061] According to an embodiment of the present invention, when the contact is performed, the reaction time is 10-40 minutes and the reaction temperature is 20-35°C.

[0062] According to an embodiment of the present invention, in step S2, the elution process is performed using an elution solution.

[0063] According to an embodiment of the present invention, the elution solution contains an antigen-antibody complex dissociation reagent.

[0064] According to an embodiment of the present invention, the antigen-antibody complex dissociation reagent includes at least one selected from an organic acid solution, an inorganic acid solution, and an alkaline solution.

[0065] The organic acid solution comprises at least one selected from the group consisting of formic acid solution, acetic acid solution, trifluoroacetic acid solution, propionic acid solution, glycolic acid solution, amino acid solution, butyric acid solution, citric acid, succinic acid, ascorbic acid, lactic acid, malic acid, and tartaric acid;

[0066] The inorganic acid solution comprises at least one selected from hydrochloric acid solution, sulfuric acid solution, and phosphoric acid solution;

[0067] The alkaline solution includes at least one selected from sodium hydroxide solution, potassium hydroxide solution, tris(hydroxymethyl)aminomethane solution, tetraethylammonium bromide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium bicarbonate solution, ammonia solution, and urea solution.

[0068] According to an embodiment of the present invention, the antigen-antibody complex dissociation reagent is a trifluoroacetic acid solution.

[0069] According to an embodiment of the present invention, the mass concentration of the trifluoroacetic acid solution is 0.05-5%.

[0070] According to an embodiment of the present invention, the method further comprises, before step S2, washing the antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains.

[0071] According to an embodiment of the present invention, the cleaning process is performed using a cleaning liquid.

[0072] According to an embodiment of the present invention, the cleaning solution includes at least one selected from PBS, PBST, and TBST solutions.

[0073] According to an embodiment of the present invention, the cleaning solution is PBST solution.

[0074] According to an embodiment of the present invention, step S3 further includes mixing the solution to be tested with a matrix solution, spotting the mixed solution on a sample chip, and performing a crystallization process.

[0075] According to an embodiment of the present invention, the matrix in the matrix liquid includes at least one selected from sinapinic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, anthracene triol, and 3-indole acrylic acid.

[0076] According to an embodiment of the present invention, the matrix in the matrix liquid is sinapinic acid.

[0077] According to an embodiment of the present invention, the volume ratio of the test solution and the matrix solution when mixed is 1:(1-10).

[0078] According to an embodiment of the present invention, the method includes:

[0079] (1) when detecting whether the sample to be tested contains free light chains, based on the MALDI-TOFMS detection result obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the sample to be tested contains free light chains; or

[0080] (2) When it is necessary to detect whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type, based on the type of the antibody in the antibody-bound magnetic beads used in step S1 and the MALDI-TOF MS detection results obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type,

[0081] In case (1), in step S1, magnetic beads bound to a κ-type free light chain-specific antibody and magnetic beads bound to a λ-type free light chain-specific antibody are mixed and brought into contact with a sample to be tested;

[0082] In case (2), in step S1, the magnetic beads bound to the κ-type free light chain specific antibody and the magnetic beads bound to the λ-type free light chain specific antibody are mixed and contacted with the sample to be tested respectively.

[0083] According to an embodiment of the present invention, the sample to be tested is a serum sample, a urine sample, a cerebrospinal fluid sample or a whole blood sample. The detection method of the present invention is particularly suitable for the detection and typing of free light chains in urine samples.

[0084] The present invention provides a new FLC detection method. By using magnetic beads bonded with κ-type and λ-type FLC-specific antibodies, the two types of FLC in the test sample (such as urine) are enriched respectively. After elution, the two types of FLC are detected by MALDI-TOF MS. The results are automatically analyzed by software and the presence of monoclonal FLC in the test sample (such as urine) and its specific type are determined. The present invention solves the problem of accurately characterizing and typing monoclonal FLC in the test sample (such as urine). Compared with the uIFE method, the detection method provided by the present invention has higher sensitivity, better accuracy, simpler operation, and easier automation, and does not have the subjective problem of manual interpretation. Compared with other mass spectrometry methods, such as liquid chromatography-tandem mass spectrometry, the detection cost is lower, the operation is simpler and easier to automate, and the detection throughput is higher, making it easier to promote in clinical diagnosis and treatment.

[0085] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0087] Figures 1a-1c The difference in the enrichment ability of κ-FLC-specific antibody magnetic beads bound with 1 / 10, 1 / 100, and 1 / 1000 antibody-magnetic-bead mass ratios for FLC in negative urine samples is shown.

[0088] Figure 2 The detection limit of the present invention's detection method for monoclonal FLC in urine samples is shown;

[0089] Figure 3a 、 3bThe results of the present invention are shown for the detection of urine samples with clinical uIFE detection results of κ-type FLC monoclonal positive / λ-type FLC monoclonal negative;

[0090] Figure 3c 、 3d The results of the method of the present invention are shown for the detection of urine samples with clinical uIFE detection results of both κ-type and λ-type monoclonal FLC being negative. DETAILED DESCRIPTION

[0091] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0092] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0093] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0094] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meaning commonly understood by those skilled in the art to which the present invention belongs.

[0095] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention, but not excluding other contents.

[0096] As used herein, the terms "optionally," "optional," or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0097] According to a specific embodiment of the present invention, the present invention provides a kit for detecting or typing free light chains in a sample, comprising:

[0098] Antibody-bound magnetic beads;

[0099] elution solution;

[0100] Reaction buffer;

[0101] Wherein, the antibody is a κ-type and / or λ-type free light chain specific antibody,

[0102] The elution solution contains an antigen-antibody complex dissociation reagent,

[0103] The mass ratio of the antibody to the magnetic beads is 1:(10-1000),

[0104] The particle size of the magnetic beads is 0.5-5 μm.

[0105] It should be noted that the free light chains and FLC (free light chains) in the present invention have the same meaning and can be interchanged.

[0106] It should be noted that the kit provided by the present invention may contain magnetic beads bonded to κ-type free light chain-specific antibodies, or magnetic beads bonded to λ-type free light chain-specific antibodies, or magnetic beads bonded to both κ-type and λ-type free light chain-specific antibodies. The antibodies in the antibody-bonded magnetic beads can be adjusted according to different detection requirements.

[0107] According to a specific embodiment of the present invention, the κ-type or λ-type free light chain-specific antibody is a specific anti-human κ-type or λ-type free light chain antibody or a fragment thereof. According to a specific embodiment of the present invention, the κ-type or λ-type free light chain-specific antibody is a monoclonal antibody or a polyclonal antibody or a fragment thereof. According to a specific embodiment of the present invention, the κ-type or λ-type free light chain-specific antibody is a polyclonal antibody.

[0108] According to a specific embodiment of the present invention, the affinity constant KD value of the κ-type and λ-type free light chain specific antibody is 100-100000 pM. For example, in the kit, the affinity constant KD value of the κ-type and λ-type free light chain specific antibody can be any value in the range of 100-100000 pM, including but not limited to 100 pM, 500 pM, 1000 pM, 5000 pM, 10000 pM, 50000 pM, 100000 pM, etc.

[0109] According to a specific embodiment of the present invention, in the kit, the ratio of the magnetic beads bonded to the κ-type free light chain-specific antibody to the magnetic beads bonded to the λ-type free light chain-specific antibody is (1-10): 1. For example, in the kit, the ratio of the magnetic beads bonded to the κ-type free light chain-specific antibody to the magnetic beads bonded to the λ-type free light chain-specific antibody is any value from (1-10): 1, including but not limited to 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0110] According to a specific embodiment of the present invention, the surface of the magnetic beads is modified with a protein or chemical group, and the protein or chemical group is used to bind to the antibody. It should be noted that there are no special restrictions on the protein or chemical group. All proteins or groups that can be used for in vitro detection to connect proteins to magnetic beads are covered by the protection scope of the present invention. For example, the chemical group includes but is not limited to at least one of amino, carboxyl, epoxy, and hydroxyl groups; the protein includes but is not limited to streptavidin. According to a specific embodiment of the present invention, when the surface of the magnetic beads is modified with streptavidin, the antibody is linked to biotin.

[0111] According to a specific embodiment of the present invention, the particle size of the magnetic beads in the kit is 0.5-5 μm. For example, in the kit, the particle size of the magnetic beads can be any value within the range of 0.5-5 μm, including but not limited to 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, etc.

[0112] Regarding the particle size of the magnetic beads, the inventors have found that a particle size of 0.5-5 μm can further improve the sensitivity and accuracy of the detection results. Preferably, the particle size of the magnetic beads is 2.5 μm.

[0113] According to a specific embodiment of the present invention, when the mass ratio of the antibody to the magnetic beads is 1:(10-1000), the antibody-magnetic beads bound at this ratio can further improve the detection sensitivity of the sample FLC. In the kit, the mass ratio of the antibody to the magnetic beads can be any value within the range of 1:(10-1000), for example, 1:10, 1:50, 1:100, 1:200, 1:300, 1:400, 1:500, 1:1000, etc. Preferably, the mass ratio of the antibody to the magnetic beads is 1:100.

[0114] According to a specific embodiment of the present invention, the antigen-antibody complex dissociation reagent is not particularly limited, and all reagents that can be used to dissociate the antigen-antibody complex and have no effect on the antigen-antibody itself are covered within the scope of protection of the present invention. According to a specific embodiment of the present invention, the antigen-antibody complex dissociation reagent includes but is not limited to at least one of an organic acid solution, an inorganic acid solution, and an alkaline solution, and the organic acid solution includes at least one selected from formic acid solution, acetic acid solution, trifluoroacetic acid solution, propionic acid solution, hydroxyacetic acid solution, amino acid solution, butyric acid solution, citric acid, succinic acid, ascorbic acid, lactic acid, malic acid, and tartaric acid; the inorganic acid solution includes at least one selected from hydrochloric acid solution, sulfuric acid solution, and phosphoric acid solution; the alkaline solution includes at least one selected from sodium hydroxide solution, potassium hydroxide solution, trishydroxymethylaminomethane solution, tetraethylammonium bromide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium bicarbonate solution, ammonia solution, and urea solution.

[0115] According to a specific embodiment of the present invention, the antigen-antibody complex dissociation reagent is a trifluoroacetic acid solution having a mass concentration of 0.05-5%.

[0116] According to a specific embodiment of the present invention, the reaction buffer comprises at least one selected from PBS, PBST, and TBST solutions. Preferably, the reaction buffer is PBST solution.

[0117] According to a specific embodiment of the present invention, the kit further comprises a cleaning solution; the cleaning solution comprises at least one selected from PBS, PBST, and TBST solutions. Preferably, the cleaning solution is PBST solution.

[0118] It should be noted that when the reaction buffer and the cleaning solution in the kit are the same reagent, for example, both are PBST solutions, then the reagent in the kit can be used as both the reaction buffer and the cleaning solution.

[0119] According to a specific embodiment of the present invention, the kit further comprises a matrix solution for MALDI-TOF MS detection.

[0120] It should be noted that there are no particular limitations on the composition of the matrix liquid; all types of matrix liquids suitable for MALDI-TOF MS detection are encompassed within the scope of the present invention. According to a specific embodiment of the present invention, the matrix in the matrix liquid can be selected from at least one of sinapinic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, anthracenetriol, and 3-indoleacrylic acid. According to a preferred embodiment of the present invention, the matrix in the matrix liquid is sinapinic acid.

[0121] According to a specific embodiment of the present invention, the present invention provides a urine FLC detection kit based on time-of-flight mass spectrometry technology, comprising:

[0122] Reagent components include magnetic beads bound with κ-type and λ-type FLC-specific antibodies, sample diluent (reaction buffer), washing solution, eluent, matrix solution, etc.

[0123] According to a specific embodiment of the present invention, the present invention provides a method for detecting free light chains in a sample, the method comprising using the aforementioned kit for detecting or typing free light chains in a sample to detect the sample to be tested, so as to determine whether the sample to be tested contains free light chains, or to type the free light chains into κ type or λ type.

[0124] According to a specific embodiment of the present invention, the present invention provides a method for detecting free light chains in a sample, comprising:

[0125] S1: contacting a sample to be tested and antibody-bound magnetic beads in a reaction buffer, so that the κ-type and / or λ-type free light chains contained in the sample to be tested specifically bind to the antibodies bound to the magnetic beads, thereby obtaining antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains;

[0126] S2: performing an elution treatment and a magnetic separation treatment on the antigen-antibody complex magnetic beads to elute and separate the enriched κ and / or λ free light chains from the antibody-bound magnetic beads to obtain a test solution containing κ and / or λ free light chains;

[0127] S3: Spot the test solution on the sample chip, perform crystallization treatment, and use MALDI-TOF MS to detect whether the test sample contains free light chains, or perform κ type and λ type typing of the free light chains.

[0128] Wherein, the antibodies are κ-type and λ-type free light chain specific antibodies.

[0129] According to a specific embodiment of the present invention, in step S1, when contacting, the volume ratio of the sample to be tested to the reaction buffer is 1:(1-200).

[0130] According to a specific embodiment of the present invention, the mass concentration of the antibody-bound magnetic beads in the reaction buffer is 1-100 mg / mL. For example, the mass concentration of the antibody-bound magnetic beads in the reaction buffer can be 1 mg / mL, 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, 100 mg / mL, etc.

[0131] According to a specific embodiment of the present invention, when the contact is carried out, the reaction time is 10-40 minutes and the reaction temperature is 20-35°C.

[0132] According to a specific embodiment of the present invention, in step S2, the elution treatment is performed using an elution solution. According to a specific embodiment of the present invention, the elution solution contains an antigen-antibody complex dissociation reagent, and the type of the antigen-antibody complex dissociation reagent is as described above.

[0133] According to a specific embodiment of the present invention, the method further comprises, before step S2, washing the antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains.

[0134] According to a specific embodiment of the present invention, the cleaning process is performed using a cleaning liquid, and the type of the cleaning liquid is as described above.

[0135] According to a specific embodiment of the present invention, step S3 further comprises mixing the test solution with a matrix solution, spotting the mixed solution on a sample chip, and performing a crystallization process. The type of matrix in the matrix solution is as described above.

[0136] According to a specific embodiment of the present invention, the volume ratio of the test solution and the matrix solution when mixed is 1:(1-10).

[0137] According to a specific embodiment of the present invention, the method comprises:

[0138] (1) when detecting whether the sample to be tested contains free light chains, based on the MALDI-TOFMS detection result obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the sample to be tested contains free light chains; or

[0139] (2) When it is necessary to detect whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type, based on the type of the antibody in the antibody-bound magnetic beads used in step S1 and the MALDI-TOF MS detection results obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type,

[0140] In case (1), in step S1, magnetic beads bound to a κ-type free light chain-specific antibody and magnetic beads bound to a λ-type free light chain-specific antibody are mixed and brought into contact with a sample to be tested;

[0141] In case (2), in step S1, the magnetic beads bound to the κ-type free light chain specific antibody and the magnetic beads bound to the λ-type free light chain specific antibody are mixed and contacted with the sample to be tested respectively.

[0142] According to a specific embodiment of the present invention, the sample to be tested is a serum sample, a urine sample, a cerebrospinal fluid sample or a whole blood sample.

[0143] According to a specific embodiment of the present invention, the present invention provides a method for detecting free light chains in urine, comprising:

[0144] 1) Sample dilution: Take a certain amount of fresh urine sample and dilute it with buffer solution by a certain multiple;

[0145] The urine sample volume can be selected from 5 μL to 100 μL, preferably 20 μL;

[0146] The buffer solution can be PBS, PBST, TBST solution, etc., preferably PBST;

[0147] The dilution multiple can be selected in the range of 1 to 200 times, preferably 20 times.

[0148] 2) FLC enrichment: Add a certain amount of magnetic beads bound to κ- or λ-type FLC-specific antibodies to the sample diluent, mix thoroughly, and incubate for a period of time;

[0149] The κ-type or λ-type FLC-specific antibody may be a specific anti-human κ-type or λ-type FLC complete antibody or a fragment thereof, and may be a monoclonal or polyclonal complete antibody or a fragment thereof, preferably a polyclonal complete antibody;

[0150] The particle size of the antibody-bound magnetic beads can be in the range of 0.5 μm to 5 μm, preferably 2.5 μm; the surface modification groups of the magnetic beads can be selected from streptavidin, amino, carboxyl, epoxy, etc., preferably streptavidin magnetic beads;

[0151] The mass ratio of antibody to magnetic beads can be selected from 1 / 10 to 1 / 1000, with a preferred ratio of 1 / 100.

[0152] The mass range of the antibody-bound magnetic beads added to the sample diluent can be 0.01 mg to 1 mg, with the preferred addition amount being 0.1 mg;

[0153] The incubation time of the antibody-bound magnetic beads and the sample can be selected from 10 min to 40 min, preferably 20 min, and the incubation temperature can be selected from 20° C. to 35° C., preferably 25° C.

[0154] 3) Sample cleaning: The magnetic beads that have completed FLC enrichment and the sample diluent are magnetically separated, and the magnetic beads are washed multiple times. After the washing is completed, the magnetic beads and the washing solution are magnetically separated, and the washing solution is discarded.

[0155] The magnetic bead washing solution can be deionized water, PBS, PBST, TBST solution, etc. The washing times can be 3 to 5 times. The preferred washing steps are: washing twice with 600 μL PBST solution and washing once with 600 μL deionized water.

[0156] 4) Sample elution: Use a certain amount of eluent to elute the FLC enriched on the magnetic beads, perform magnetic separation, and remove the eluent.

[0157] The eluent may be trifluoroacetic acid aqueous solution, acetic acid aqueous solution, formic acid aqueous solution, etc., and the concentration range may be 0.1% to 5%, preferably 0.1% trifluoroacetic acid aqueous solution.

[0158] The amount of eluent added can be selected in the range of 5 μL to 50 μL, preferably 10 μL.

[0159] 5) Spotting: Mix the eluate and matrix solution in a 1:1 volume ratio and spot it on the sample chip. After drying and crystallization, place it in the mass spectrometry system for collection.

[0160] The matrix liquid can be selected from sinapinic acid, α-cyano-4-hydroxycinnamic acid, dihydroxybenzoic acid, etc., preferably sinapinic acid.

[0161] Sample collection: Load the dried and crystallized sample chip into the mass spectrometer and set the mass spectrometer acquisition conditions, including: laser energy 5-25 μJ, detector voltage 0.4-0.7 kV, focus mass 20,000-25,000 Da, scan speed 0.5-1.5 mm / s, scan range 2,000-200,000 Da; linear positive ion mode.

[0162] Result interpretation: The automatic sample interpretation software determines whether the sample contains monoclonal FLC based on the presence of a clear peak in the mass-to-charge ratio (m / z) range of 22 kDa to 24.5 kDa, and interprets the specific typing based on the type of antibody used for sample enrichment.

[0163] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0164] Example 1 Detection of urine FLC

[0165] 1. Urine Sample Pretreatment

[0166] (1) Sample dilution: Take 20 μL of fresh urine sample and dilute it 20 times with PBST buffer.

[0167] (2) FLC enrichment: Add magnetic beads bound to κ-type or λ-type FLC-specific antibodies to the sample diluent, mix thoroughly, and incubate for a period of time.

[0168] The κ- or λ-FLC-specific antibody is a complete polyclonal antibody specific for human κ- or λ-FLC; the magnetic beads bound to the antibody have a particle size of 2.5 μm; and the surface modification group of the magnetic beads is streptavidin;

[0169] The mass ratio of antibody to magnetic beads is 1 / 100. At this ratio, the antibody-magnetic beads have the best detection sensitivity for FLC in urine samples.

[0170] The amount of antibody-bound magnetic beads added to the sample diluent was 0.1 mg;

[0171] The antibody-bound magnetic beads were incubated with the sample for 20 min at a temperature of 25°C.

[0172] (3) Sample cleaning: The magnetic beads that have completed FLC enrichment and the sample diluent are magnetically separated, and the magnetic beads are washed multiple times. After the washing is completed, the magnetic beads and the washing solution are magnetically separated and the washing solution is discarded.

[0173] The cells were washed twice with 600 μL of PBST solution and once with 600 μL of deionized water.

[0174] (4) Sample elution: The FLC enriched on the magnetic beads was eluted with 10 μL of 0.1% trifluoroacetic acid aqueous solution, and magnetic separation was performed, and the eluate was removed.

[0175] (5) Spotting: Mix the eluate and matrix solution at a volume ratio of 1:1 and spot the mixture on the sample chip. After drying and crystallization, place the sample on the mass spectrometer for collection. The matrix solution is sinapinic acid.

[0176] 2. Sample collection:

[0177] The dried and crystallized sample chip was loaded into the mass spectrometer, and the mass spectrometer acquisition conditions were set, including: laser energy 10 μJ, detector voltage 0.5 kV, focus mass 22000 Da, scanning speed 1.0 mm / s, scanning range 2000-200000 Da; linear positive ion mode.

[0178] 3. Interpretation of results:

[0179] The automatic sample interpretation software determines whether the sample contains monoclonal FLC based on the presence of a clear peak in the mass-to-charge ratio (m / z) range of 22 kDa to 24.5 kDa, and interprets the specific typing based on the antibody type information used for sample enrichment.

[0180] Example 2 Detection of urine FLC

[0181] Ten monoclonal FLC-negative urine samples were mixed and serially diluted with 1xPBS at dilution ratios of 2, 10, and 100, respectively. 20 μL of the original mixture and the three dilutions were added to 380 μL of PBST. Each dilution was enriched with 0.1 mg of κ-FLC-specific antibody magnetic beads bound to 1 / 10, 1 / 100, and 1 / 1000 antibody magnetic beads (the affinity constant KD value of the κ-FLC-specific antibody was 10,000 pM). Subsequent sample washing, sample elution, and spot testing were performed (for the detection steps, refer to Example 1). Figure 1a 、 1b 1c and 1d respectively show the enrichment ability of FLC in negative urine samples by κ-type FLC-specific antibody magnetic beads bonded with antibody magnetic beads at a mass ratio of 1 / 10, 1 / 100, and 1 / 1000. Figure 1b The results showed that using antibody magnetic beads with a mass ratio of 1 / 100 for sample enrichment could detect FLC in urine diluted at least 10 times.

[0182] Ten monoclonal FLC-negative urine samples were selected and mixed and packaged. Different concentrations of monoclonal κ-FLC were added to prepare urine samples containing 0.01 mg / mL, 0.05 mg / mL, and 0.1 mg / mL monoclonal κ-FLC. 20 μL of each dilution was added to 380 μL PBST. Each dilution was enriched with 0.1 mg of κ-FLC-specific antibody magnetic beads bonded at a 1 / 100 antibody magnetic bead mass ratio. Subsequent sample washing, sample elution, and spot testing were performed (see Example 1 for the detection steps). Figure 2 The results showed that the present method has the ability to detect monoclonal FLC in urine samples as low as 0.01 mg / mL.

[0183] Example 3 Detection of FLC in patients with monoclonal immunoglobulin

[0184] Two urine samples that were clinically uIFE-positive for κ-type FLC monoclonal / negative for λ-type FLC and negative for both κ-type and λ-type monoclonal FLC were tested. Each sample was diluted and enriched with 0.1 mg of κ-type and λ-type FLC-specific antibody magnetic beads bonded at a 1 / 100 antibody magnetic bead mass ratio, respectively. Subsequent sample washing, sample elution and spot testing were performed (the ratio of κ-type FLC-specific antibody magnetic beads to λ-type FLC-specific antibody magnetic beads used was 1:1). Figure 3a and 3b This is the test result of this protocol for urine samples with clinical uIFE test results of κ-type FLC monoclonal positive / λ-type FLC monoclonal negative. Figure 3c and 3d The results of this protocol on a urine sample that was negative for both κ-type and λ-type monoclonal FLC in clinical uIFE testing were presented. These results demonstrate the protocol's ability to detect FLC in actual clinical urine samples and its comparability with clinical urine FLC detection methods.

[0185] Example 4 Comparative test of 30 clinical urine samples tested by uIFE

[0186] Thirty urine samples collected from clinical uIFE patients were tested for FLC using the present method. Comparative results for two types of FLC (κ and λ) are shown in Tables 1 and 2. The present method and uIFE demonstrated 100% concordance for detecting monoclonal positive FLC samples of both types, 92% for detecting monoclonal negative FLC samples of κ type, and 95.4% for detecting monoclonal negative FLC samples of λ type. The present method demonstrated a higher detection rate for monoclonal positive FLC samples than the uIFE method.

[0187] Table 1

[0188]

[0189] Table 2

[0190]

[0191] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", "some implementation plans" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0192] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A kit for detecting or typing free light chains in a sample, characterized in that: include: Antibody-bound magnetic beads; elution solution; Reaction buffer; Wherein, the antibody is a κ-type and λ-type free light chain specific antibody, The elution solution contains an antigen-antibody complex dissociation reagent, The mass ratio of the antibody to the magnetic beads is 1:(10-1000), The particle size of the magnetic beads is 0.5-5 μm.

2. The kit according to claim 1, wherein The κ-type and λ-type free light chain specific antibodies are specific anti-human κ-type or λ-type free light chain antibodies or fragments thereof; Optionally, the κ-type or λ-type free light chain-specific antibody is a monoclonal antibody or a polyclonal antibody or a fragment thereof; Optionally, the κ-type and λ-type free light chain-specific antibodies are polyclonal antibodies; Optionally, the affinity constant KD value of the κ-type and λ-type free light chain-specific antibody is 100-100000 pM; Optionally, in the kit, the ratio of the magnetic beads bound to the κ-type free light chain-specific antibody to the magnetic beads bound to the λ-type free light chain-specific antibody is (1-10):

1.

3. The kit according to claim 1, wherein The surface of the magnetic beads is modified with proteins or chemical groups, and the proteins or chemical groups are used to bind to the antibodies; Optionally, the chemical group includes at least one selected from amino, carboxyl, epoxy, and hydroxyl groups; Optionally, the protein is streptavidin; Optionally, when the surface of the magnetic beads is modified with streptavidin, the antibody is linked to biotin.

4. The kit according to claim 1, wherein The antigen-antibody complex dissociation reagent includes at least one selected from an organic acid solution, an inorganic acid solution, and an alkaline solution; The organic acid solution comprises at least one selected from the group consisting of formic acid solution, acetic acid solution, trifluoroacetic acid solution, propionic acid solution, glycolic acid solution, amino acid solution, butyric acid solution, citric acid, succinic acid, ascorbic acid, lactic acid, malic acid, and tartaric acid; The inorganic acid solution comprises at least one selected from hydrochloric acid solution, sulfuric acid solution, and phosphoric acid solution; The alkaline solution includes at least one selected from the group consisting of sodium hydroxide solution, potassium hydroxide solution, tris(hydroxymethyl)aminomethane solution, tetraethylammonium bromide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium bicarbonate solution, ammonia solution, and urea solution; Optionally, the antigen-antibody complex dissociation reagent is a trifluoroacetic acid solution; Optionally, the mass concentration of the trifluoroacetic acid solution is 0.05-5%.

5. The kit according to claim 1, wherein The reaction buffer comprises at least one selected from PBS, PBST, and TBST solutions; Optionally, the reaction buffer is PBST solution.

6. The kit according to claim 1, wherein The kit further comprises a cleaning solution; Optionally, the cleaning solution comprises at least one selected from PBS, PBST, and TBST solutions; Optionally, the cleaning solution is PBST solution.

7. The kit according to claim 1, wherein The kit further comprises a matrix solution for MALDI-TOFMS detection; Optionally, the matrix in the matrix solution includes at least one selected from the group consisting of sinapinic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, anthracenetriol, and 3-indoleacrylic acid; Optionally, the matrix in the matrix solution is sinapinic acid.

8. A method for detecting free light chains in a sample, characterized in that: The method comprises using the kit for detecting or typing free light chains in a sample according to any one of claims 1 to 7 to detect the sample to be tested, so as to determine whether the sample to be tested contains free light chains, or to type the free light chains into κ type or λ type.

9. A method for detecting free light chains in a sample, characterized in that: include: S1: contacting a sample to be tested and antibody-bound magnetic beads in a reaction buffer, so that the κ-type and / or λ-type free light chains contained in the sample to be tested specifically bind to the antibodies bound to the magnetic beads, thereby obtaining antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains; S2: performing an elution treatment and a magnetic separation treatment on the antigen-antibody complex magnetic beads to elute and separate the enriched κ and / or λ free light chains from the antibody-bound magnetic beads to obtain a test solution containing κ and / or λ free light chains; S3: Spot the test solution on the sample chip, perform crystallization treatment, and use MALDI-TOF MS to detect whether the test sample contains free light chains, or perform κ type and λ type typing of the free light chains. Wherein, the antibodies are κ-type and λ-type free light chain specific antibodies.

10. The method according to claim 9, characterized in that In the antibody-bound magnetic beads, the mass ratio of the antibody to the magnetic beads is 1:(10-1000); Optionally, the particle size of the magnetic beads is 0.5-5 μm; Optionally, the surface of the magnetic beads is modified with proteins or chemical groups, and the proteins or chemical groups are used to bind to the antibodies; Optionally, the chemical group includes at least one selected from amino, carboxyl, epoxy, and hydroxyl groups; Optionally, the protein is streptavidin; Optionally, when the surface of the magnetic beads is modified with streptavidin, the antibody is linked to biotin; Optionally, the κ-type or λ-type free light chain specific antibody is a specific anti-human κ-type or λ-type free light chain antibody or a fragment thereof; Optionally, the κ-type or λ-type free light chain-specific antibody is a monoclonal antibody or a polyclonal antibody or a fragment thereof; Optionally, the κ-type and λ-type free light chain-specific antibodies are polyclonal antibodies; Optionally, the affinity constant KD value of the κ-type and λ-type free light chain-specific antibody is 100-100000 pM; Optionally, the ratio of the magnetic beads bonded to the κ-type free light chain specific antibody to the magnetic beads bonded to the λ-type free light chain specific antibody is (1-10):1; Optionally, the reaction buffer comprises at least one selected from PBS, PBST, and TBST solutions; Optionally, the reaction buffer is PBST solution.

11. The method according to claim 9, characterized in that In step S1, when contacting, the volume ratio of the sample to be tested to the reaction buffer is 1:(1-200); Optionally, in the reaction buffer, the mass concentration of the antibody-bound magnetic beads is 1-100 mg / mL. Optionally, when contacting, the reaction time is 10-40 minutes and the reaction temperature is 20-35°C.

12. The method according to claim 9, characterized in that In step S2, the elution treatment is performed using an elution solution; Optionally, the elution solution contains an antigen-antibody complex dissociation reagent, Optionally, the antigen-antibody complex dissociation reagent comprises at least one selected from an organic acid solution, an inorganic acid solution, and an alkaline solution; The organic acid solution comprises at least one selected from the group consisting of formic acid solution, acetic acid solution, trifluoroacetic acid solution, propionic acid solution, glycolic acid solution, amino acid solution, butyric acid solution, citric acid, succinic acid, ascorbic acid, lactic acid, malic acid, and tartaric acid; The inorganic acid solution comprises at least one selected from hydrochloric acid solution, sulfuric acid solution, and phosphoric acid solution; The alkaline solution includes at least one selected from the group consisting of sodium hydroxide solution, potassium hydroxide solution, tris(hydroxymethyl)aminomethane solution, tetraethylammonium bromide solution, sodium carbonate solution, sodium bicarbonate solution, ammonium bicarbonate solution, ammonia solution, and urea solution; Optionally, the antigen-antibody complex dissociation reagent is a trifluoroacetic acid solution; Optionally, the mass concentration of the trifluoroacetic acid solution is 0.05-5%.

13. The method according to claim 11 or 12, characterized in that The method further comprises, before step S2, washing the antigen-antibody complex magnetic beads enriched with κ-type and / or λ-type free light chains; Optionally, the cleaning process is performed using a cleaning liquid; Optionally, the cleaning solution comprises at least one selected from PBS, PBST, and TBST solutions; Optionally, the cleaning solution is PBST solution.

14. The method according to claim 9, characterized in that Step S3 further includes mixing the test solution with a matrix solution, spotting the mixed solution on a sample chip, and performing a crystallization process; Optionally, the matrix in the matrix solution includes at least one selected from the group consisting of sinapinic acid, α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, anthracenetriol, and 3-indoleacrylic acid; Optionally, the matrix in the matrix solution is sinapinic acid; Optionally, the volume ratio of the test solution and the matrix solution when mixed is 1:(1-10).

15. The method according to claim 9, characterized in that The method comprises: (1) when detecting whether the sample to be tested contains free light chains, based on the MALDI-TOF MS detection result obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the sample to be tested contains free light chains; or (2) When it is necessary to detect whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type, based on the type of the antibody in the antibody-bound magnetic beads used in step S1 and the MALDI-TOF MS detection results obtained in step S3, whether a peak signal exists within the mass-to-charge ratio m / z range of 22 kDa to 24.5 kDa, so as to determine whether the free light chains contained in the sample to be tested are of the κ type and / or the λ type, In case (1), in step S1, magnetic beads bound to a κ-type free light chain-specific antibody and magnetic beads bound to a λ-type free light chain-specific antibody are mixed and brought into contact with a sample to be tested; In case (2), in step S1, the magnetic beads bound to the κ-type free light chain specific antibody and the magnetic beads bound to the λ-type free light chain specific antibody are mixed and contacted with the sample to be tested respectively.

16. The method according to claim 9, characterized in that The sample to be tested is a serum sample, a urine sample, a cerebrospinal fluid sample or a whole blood sample.

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