ANTIHUMAN STROMELYSIN MONOCLONAL ANTIBODY AND DIAGNOSIS OF RHEUMATOID ARTHRITIS BY ENZYME IMMUNOASSAY

Abstract: The invention provides as an antibody against human stromelysin a monoclonal antibody which has an immunoreactivity with only one of the antigenic determinants present in human stromelysin and reacts with either of cryptic and active stromelysins indiscriminatingly. The concurrent use of two kinds of monoclonal antibodies, each of which specifically combines with one of the two different antigenic determinants of human stromelysin, allows human stromelysin present in the bodily fluid to be accurately determined, thus enabling diagnosis of rheumatoid arthritis. The invention provides a method of enzyme immumoassay of human stromelysin present in the bodily fluid by the sandwich technique using the above monoclonal antibody itself and two kinds thereof, and a method of diagnosing rheumatoid arthritis thereby.

Description: FIELD OF THE INVENTION The present invention relates to anti-human stromelysin monoclonal antibodies, an enzyme immunoassay using such monoclonal antibodies and a method for the diagnosis of rheumatoid arthritis by determination, on the basis of said immunoassay, of the amount of human stromelysin present in samples as the sum of the amount of latent stromelysin and that of active stromelysin. BACKGROUND ART Stromelysin, also called proteoglycanase or MMP-3 (matrix metalloproteinase-3), is a substance produced in fibroblasts or tumor cells stimulated by different cytokines, growth factors, etc. In the live body, it is existent in bloods or synovial fluids, besides being produced locally in joints of patients with rheumatoid arthritis. Stromelysin has been considered to play an important role in the intraarticular cartilage destruction in patients with rheumatoid arthritis since it decomposes gelatin, laminin, type IV collagen, fibronectin etc. in addition to proteoglycan and type IX collagen, both being important extracellular matrix for articular cartilage. Stromelysin is produced in the latent form, also called prostromelysin which is converted, by activation in the extracellular matrix, into active stromelysin. The latent stromelysin, when treated with serine proteases such as plasmin or trypsin, undergoes restricted decomposition into active stromelysin. The active stromelysin also forms when the latent stromelysin is treated with 4-aminophenylmercuric acetate (APMA). The latent stromelysin has a molecular weight (Mr) of either 57,000 dalton (57 kD) or 59,000 (59 kD), the 59 kD stromelysin being a glycosylated form of the 57 kD stromelysin. Furthermore, the active stromelysin resulting from the protease digestion shows a Mr of 45 kD. The active stromelysin obtained by the APMA treatment shows Mr of 45 kD and 46 kD, while a lower active stromelysin with Mr 28 kD is obtained by extending the APMA treatment duration to 12 hours or more. For the diagnosis of rheumatoid arthritis have heretofore been used Rose's method based on the detection of rheumatoid factor, modified Rose's method by Heller, RAHA-test, RA-test, etc. These methods, however, have such advantages that blood rheumatoid factor is not specific to patients with rheumatoid arthritis and that rheumatoid factor assay kits based on such methods are poor in accuracy or reproducibility. Assays for erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), although rendering it possible to learn the activity of the above mentioned disease, are not suitable for the diagnosis thereof. With the detection of anti-nuclear antibodies or LE cells, it is difficult to conduct accurate diagnosis of rheumatoid arthritis because it is poor in specificity to the disease and also because such antibodies or cells are frequently detectable in other collagen diseases. There also exist methods of determining hyaluronic acid, but they are inconvenient in that only synovial fluids are usable as samples. Cooksley et al., Matrix, 10[5] (1990), 285-291 measure stromelysin in an enzyme linked immunosorbent assay (ELISA) using a monoclonal antibody raised with the natural human protein as an antigen and polyclonal antibodies raised with a recombinant stromelysin as an antigen MacNaul et al., Journal of Biological Chemistry, 265[28](1990), 17238-17245 detect stromelysin in cell culture supernatants with an immunoblot assay using a monoclonal antibody whose specificity is examined by the use of purified recombinant stromelysin. Case et al., American Journal of Pathology, 135[6](1989), 1055-1064 used for immunohistochemistry a rabbit polyclonal antibody against the 17-mer synthetic peptide according to stromelysin amino acid sequence 455-470 with an additional c-terminal cysteine residue. Furthermore, Case et al. determined the stromelysin mRNA levels from synovia of rheumatoid arthritis (RA) or osteoarthritic (OA) patients. Köhler and Milstein, Nature 256 (1975), 495-497 solve the technical problem of providing monoclonal antibodies by cell fusion technology. Human stromelysin has been found to be synthesized and secreted in large quantities locally in joints of patients with rheumatoid arthritis among other arthropathies. Stromelysin is also synthesized and secreted in synovial lining cells or joint chondrocytes of patients with osteoarthritis. However, since polyarthritis is produced in rheumatoid arthritis whereas monoarthritis is generally produced in osteoarthritis, bloods or synovial fluids of patients with osteoarthritis show no significant increase in the amount of stromelysin as compared with normal subjects. The present invention is of particular significance in respect of the diagnosis of rheumatoid arthritis, since no biochemical marker has been found so far that could serve as indicator of articular destruction as mentioned above. DISCLOSURE OF THE INVENTION This invention provides IgG-class anti-human stromelysin monoclonal antibodies and a method for the preparation thereof by way of the use of hybridomas, as well as an enzyme immunoassay for human stromelysin based on the sandwich method using said monoclonal antibodies and a method for the diagnosis of rheumatoid arthritis which comprises using said immunoassay to measure the amount of stromelysin in blood or other samples from patients with rheumatoid arthritis and comparing the measured amount with the amount of stromelysin in the corresponding samples from normal subjects. Thus, according to the present invention, there are provided: (1) Monoclonal antibodies reactive with latent stromelysin (prostromelysin) and active stromelysin without discrimination between the two, each being a monoclonal antibody having immunoreactivity with only one of the antigenic determinants of human stromelysin; (2) An enzyme immunoassay for human stromelysin characterized in that the sum of the amount of latent stromelysin (prostromelysin) and that of active stromelysin is determined by the sandwich method using a combination of two monoclonal antibodies which specifically bind to their respective different antigenic determinants of human stromelysin; and (3) A method for the diagnosis of rheumatoid arthritis comprising measuring, by way of said enzyme immunoassay, the amount of human stromelysin present in a sample as the sum of the amount of latent stromelysin and that of active stromelysin and comparing the measured amount with that for corresponding samples from normal subjects. The above mentioned enzyme immunoassay employed in the present invention will be understood from examples which will be given below. They may be selected, for example, from any conventional enzyme immunoassays of different types: competitive methods such as solid phase antibody method, double antibody method, EMIT (enzyme multiplied immunoassay technique), enzyme channeling immunoassay, enzymatic activity modifier immunoassay and liposome membrane-enzyme immunoassay, and non-competitive methods such as sandwich method, immunoenzyme metric assay, enzymatic activity enhanced immunoassay and proximal linkage immunoassay. In the above mentioned immunoassay, a variety of materials in any appropriate usage forms which well adsorb passively antigens or antibodies may be chosen for use as solid supports, e.g. polystyrenes, polycarbonates, polypropylenes or polyvinyls in such forms as balls, microplates, sticks or test tubes. As labeling enzymes may be used, for example, peroxidase, alkaline phosphatase and β-D-galactosidase. As means for determining their enzymatic activity may be used, for example, colorimetry, fluorometry, bioluminescence method or chemiluminescence method. Assays may be carried out as appropriate by using any combination of these enzymes and means for determining their enzymatic activity. As the antibody to be labeled with an enzyme, there may be used an IgG fraction obtainable by the fractionation of a material containing antibodies with ammonium sulfate followed by purification on an anion exchange gel such as DEAE-Sephacel, as well as Fab' that specifically reacts with antigen molecule and that is obtainable by its digestion with pepsin followed by reduction. Monoclonal antibodies according to the present invention, a method for the preparation thereof, an enzyme immunoassay for human stromelysin using said monoclonal antibodies and a method for the diagnosis of rheumatoid arthritis using said immunoassay will now be illustrated in more detail by way of the following examples, but it is to be understood that this invention is not limited thereto. Example 1 Preparation of monoclonal antibodies against human stromelysin (a) Preparation of antigen-human prostromelysin In accordance with the procedure described by the present inventors in Biochem. J. 254 , 731-741 (1988), synovial cells from a patient with rheumatoid arthritis were cultivated in Dalbecco-modified Eagle's medium (supplied by Nissui Seiyaku). Thus, a synovial tissue from a patient with rheumatoid arthritis who underwent arthroplasty was minced before synovial cells were liberated therefrom enzymologically. The cells were then cultivated in Dalbecco-modified Eagle's medium containing 20% fetal bovine serum, penicillin and streptomycin. The resultant cells from the primary culture in accordance with the procedure described in the literature cited above were further cultivated in a serum-free medium treated with rabbit macrophage to recover the culture on the 5th - 7th day. The thus obtained culture was processed by application to a DEAE-cellulose column (supplied by Whatman), a Green A Dye matrix column (supplied by Amicon Corp.), a gelatin Sepharose™ column, a concanavalin A Sepharose™ column (supplied by Pharmacia) and an anti-collagenase antibody-bound affinity column, finally to purify human stromelysin by the use of a Ultrogel™ AcA 44 column (supplied by LKB). When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the resultant purified human stromelysin showed a single band having a Mr about 57 kD. This purified human stromelysin is a latent form, i.e. prostromelysin. This product does not contain the 59 kD glycosylated prostromelysin because a concanavalin A Sepharose™ column was used to obtain the product in the procedure mentioned above. (b) Preparation of antibody-producing cells: Two 6-week-old female Balb/c mice were initially immunized intraperitoneally with 15 µg in 0.2 ml emulsion of purified human prostromelysin described above in (a) in Freund's complete adjuvant. The mice then received, after 17 days, a booster injection of 15 µg of the human prostromelysin dissolved in 10 mM Tris-HCl buffer (pH 7.5). As the final immunization, the mice received, after 54 days, an additional booster injection by intravenous administration of 16.5 µg/mouse of the antigen dissolved in 10 mM Tris-HCl buffer (pH 7.5). On the 3rd day after the final immunization the spleen was extirpated and the splenocytes were prepared. (c) Cell fusion: (1) Materials and methods used are as follows: RPMI 1640 culture medium: RPMI No. 1640 (Flow Lab.) supplemented with sodium bicarbonate (24 mM), sodium pyruvate (1 mM), penicillin G potassium (50 U/ml), streptomycin sulfate (50 µg/ml) and amikacin sulfate (100 µg/ml), adjusted to pH 7.2 with dry ice and filtered through a 0.2 µm Toyo membrane filter for sterilization. NS-1 culture medium: the above RPMI 1640 culture medium supplemented with 15% (v/v) filter-sterilized fetal bovine serum (M.A. Bioproducts).PEG 4,000 solution: Serum-free RPMI 1640 culture medium, containing 50% (w/w) polyethylene glycol 4,000 (PEG 4,000, Merck & Co., Inc.).Utilizing an 8-azaguanine-resistant myeloma cell line, SP-2 (SP-2/0·Ag14), cell fusion was effected according to a method of Oi et al. described in "Selected Methods in Cellular Immunology" (eds. B. B. Mishell and S. M. Shiigi, W. H. Freeman and Company, (1980), pp. 351-372). (2) The karyo-splenocytes prepared as described in the preceding (b) (cell viability 100%) were fused in a ratio of 5 to 1 with myeloma cells (cell viability 100%). Thus, the splenocytes and the myeloma cells were separately washed in RPMI 1640 culture medium, then suspended in the same medium and mixed together for fusion in the ratio described above. 37 ml of the RPMI 1640 culture medium was put into a 50 ml conical styrene resin test tube (Sumitomo Bakelite), and centrifuged at 1,000 rpm for 10 min., and the supernatant was discarded completely by suction. To the precipitated cells was added dropwise over 1 min. 4.5 ml of the PEG 4,000 solution warmed at 37°C with gentle stirring. The cells were resuspended and dispersed by stirring for another minute. To the suspension was then added dropwise over 1 min. 4.5 ml of RPMI 1640 culture medium warmed at 37°C. After repeating the same operation once more, the cells were dispersed, by adding 31.7 ml of the same culture medium dropwise over 2 to 3 min. under continuous agitation. The dispersion was centrifuged at 1,000 rpm for 7 min., and the supernatant was discarded completely by suction. To the precipitated cells was added rapidly 45 ml of NS-1 culture medium warmed at 37°C, and big cell clumps were then dispersed carefully with a 10 ml pipette. The dispersion was diluted by adding the same into a bottle containing 91 ml of the same culture medium, and distributed into 96-well microwell made of polystyrene (Iwaki Glass) so that 6.0 x 10 5 cells/0.1 ml exist in each well. The microwells were incubated at 37°C in 7% CO 2 /93% air under 100% humidity. (d) Selective proliferation of hybridomas with the aid of a selective culture medium: (1) Culture media used are as follows: HAT selection medium: the NS-1 culture medium mentioned above in (c) supplemented with hypoxanthine (100 µM), aminopterin (0.4 µM) and thymidine (16 µM). HT culture medium: the same composition as the HAT medium mentioned above except that aminopterin is not contained. (2) One day after the cultivation mentioned above in (c) was started (i.e. on the first day), two drops (ca. 0.1 ml) of HAT culture medium were added with a pipette. On the 2nd, 3rd, 5th and 8th days, the half (0.1 ml) of each culture medium was replaced with fresh HAT culture medium. On the 10th day, the half of each culture medium was replaced with fresh HT culture medium, whereupon sufficient growth of hybridoma was observed. All the wells containing hybridomas grown were tested to see if there were positive wells, using a solid phase-antibody binding test (ELISA) as will be described in the subsequent (e). All the cultures with hybridomas positive in the test above were transferred to a 24-well cell well made of polystyrene (Sumitomo Bakelite) containing 1 ml of the HT culture medium containing 10 7 mouse thymocytes as feeders. The cultures were subjected to cultivation, as described in the preceding (c), at 37°C in 7% CO 2 for five days. At the time sufficient growth of hybridomas was observed, the cultures were checked again for the positivity by the ELISA method, and subjected to a cloning procedure by the limiting dilution method as will be explained in (f) below. The residual culture after cloning was transferred into a 25 cm 2 tissue culture flask made of polystyrene (Iwaki Glass), for the preparation of a frozen sample for storage. (e) Screening for hybridomas capable of producing Anti-human stromelysin antibody by means of the solid phase-antibody binding test (ELISA): The method used for the present example was based on the method of Rennard et al. described in Anal. Biochem., 104 , 205-214, (1980), which is appropriate for the detection of antibody production in hybridoma. Each well of a 96-well microtitration plate (Flow Lab.) was coated with 30 ng/well of human stromelysin. To the wells was added a part of the supernatant from the wells containing hybridomas grown as obtained in (d) above. The incubation was carried out at room temperature for about 1 hr. After the addition of goat anti-mouse immunoglobulin (Cappel Lab.) labeled with POD as a secondary antibody, further incubation was carried out at room temperature for about 1 hr. After the addition of H 2 O 2 and o-phenylenediamine as substrate, the measurement of the absorbance at 492 nm was carried out using a microplate reader (MRP-A4, Toyo Soda). (f) Cloning: In order to obtain hybridomas capable of producing monoclonal antibodies it is necessary, after the procedure mentioned above in (d), for cloning to be carried out according to the limiting dilution method, since each well can develop two or more kinds of hybridomas. A cloning culture medium containing in NS-1 culture medium 10 7 cells per ml of mouse thymocytes as feeders was prepared. 5, 1 and 0.5/well of hybridomas were added to 36, 36 and 24 wells of a 96-well microwell, respectively. About 0.1 ml of NS-1 culture medium was further added to each well on the 5th day. On the 10th day, the half (0.1 ml) of each culture medium was replaced with fresh NS-1 culture medium. About 14 days after the cloning sufficient growth of hybridoma could be recognized, and the hybridomas were subjected to ELISA. When not all of the tested wells were shown to be positive, the colonies in antibody-positive wells were enumerated and out of them 1 well exhibiting the formation of one and single colony was selected for recloning. Finally, 14 hybridoma clones capable of producing monoclonal antibody to human stromelysin were obtained. (g) Mass production of monoclonal antibody using hybridomas: Hybridomas were proliferated in a conventional manner. Thus, monoclonal antibodies can be obtained in a concentration of 10-100 µg/ml from the supernatant of an appropriate culture medium such as NS-1 culture medium in which each of the resultant hybridomas was subjected to cultivation. If a large amount of antibody is to be produced, on the other hand, a carcinogenic excitant, Pristane (2, 6, 10, 14-tetramethylpentadecane, Aldrich Chem.), was administered to animals (Balb/c mice) intraperitoneally in a volume of 0.5 ml per animal, which animals were of the syngenic strain as those providing the splenocytes and the myeloma cells. One to 3 weeks after the administration, 1 x 10 7 cells of each hybridoma were administered intraperitoneally as above, and ascites containing 4-7 mg/ml of monoclonal antibody were obtained after 1 to 2 weeks. (h) Isotypes of monoclonal antibodies: In accordance with the above-described ELISA method, the culture supernatant for each monoclonal antibody-producing hybridoma was added to a microtitration plate coated with human stromelysin. After washing with 0.05% Tween™ 20-containing PBS, isotype-specific rabbit anti-mouse Ig antibodies (Zymed Lab.) were added thereto. After washing with PBS, goat anti-rabbit IgG (H+L) antibody labeled with POD was added thereto, and 2,2'-azino-di(3-ethylbenzthiazoline sulfonic acid) and hydrogen peroxide as substrate were then added for detection. The results are shown collectively in Table 1 described below. Out of the resultant monoclonal antibodies against human stromelysin ten antibodies were found to contain immunoglobulin chain γ 1/κ, two antibodies γ 2a/κ and two antibodies γ 2b/κ. The results for reactivity with human stromelysin were obtained in accordance with the procedure described below in (j). (i) Purification of monoclonal antibody Each of the ascites obtained in the foregoing (g) was purified by using an Affi-Gel Protein A MAPS-II kit (Bio-Rad). (j) Reactivity of human stromelysin with monoclonal antibody As described by the present inventors et al. in Biochem. J. 254 , 731-741 (1988), the conditioned medium of human synovial cells contain latent stromelysin with Mr 59 kD and 57 kD. If, however, the culture is treated with 4-aminophenyl mercuric acetate (APMA) in the presence of Ca 2+ , the latent stromelysins are activated into active stromelysin with Mr 46 kD and 45 kD. Accordingly, the above-mentioned conditioned medium containing the latent stromelysins and the APMA-treated conditioned medium containing the active stromelysins were subjected to SDS-PAGE. In accordance with the method of Tanabe as described in "Saibo Kogaku" (Cell Technology) 1 & 2, 1061-1068 (1983), Western blotting was carried out, using POD-labeled goat anti-mouse immunoglobulin, to study the reactivity of each monoclonal antibody obtained in Example 1 (i) with the latent stromelysins (59 kD and 57 kD) and with the active stromelysins (46 kD and 45 kD) . The results are shown in Table 1. As shown in Table 1, all the fourteen monoclonal antibodies were found to react with all the latent and active forms of stromelysin. Although latent collagenase or latent gelatinase are also present in the conditioned medium, only bands of 60 kD and 57 kD that correspond to the molecular weights of stromelysin were observed on the Western blotting patterns mentioned above, and no bands of 55 kD and 52 kD corresponding to the molecular weights of collagenase or 72 kD corresponding to the molecular weight of gelatinase were detected. The above-mentioned fourteen monoclonal antibodies were thus confirmed to react specifically with stromelysin but not with collagenase or gelatinase. Example 2 Immunohistologic staining using anti-human stromelysin monoclonal antibody Human stromelysin, after being produced inside a cell is continuously secreted into the exterior of the cell without being stored in the cell. Accordingly, in order to identify the cells where human stromelysin is produced, synovial tissue from patient with rheumatoid arthritis was cultivated for 3 hrs in the presence of monensin (2 µM) to accumulate human stromelysin in cells producing it. The resultant tissue was fixed with periodate-lysine-paraformaldehyde before paraffin sections were prepared. These sections were deparaffinized and endogenous peroxidase therein was blocked with hydrogen peroxide. The sections were brought into reaction with the anti-human stromelysin monoclonal antibodies (IgG) obtained in Example 1 (i). After being washed well with PBS, the sections were reacted with biotinylated horse anti-mouse IgG (H+L) and then with avidin-biotin-peroxidase complex (Vector Lab.). The thus obtained sections were washed with PBS and diaminobenzidine and hydrogen peroxide were used as substrate for color development. In the immunohistologic staining where IgG (clone 55-2A4) and IgG (clone 55-3G3) were used as anti-human stromelysin monoclonal antibody, synovial lining cells from patients with rheumatoid arthritis were stained positive, in either case, in respect of human stromelysin. It has thus been found that both clone 55-2A4 and clone 55-3G3 are usable for immunohistologic staining. The above mentioned hybridomas clones 55-2A4 and 55-3G3 have been deposited with the Fermentation Research Institute Agency of Industrial Science and Technology under accession numbers Bikoken Kinki No. 12303 (FERM P-12303) and Bikoken Kinki No. 12304 (FERM P-12304), respectively. Example 3 Quantitative method for human stromelysin (a) Preparation of enzyme-labeled monoclonal antibodies (1) Preparation of Fab' fraction Each purified monoclonal antibody (IgG) obtained in Example 1(i) was dissolved in a 0.1M acetate buffer solution(pH 4.2) and the solution was digested with pepsin as follows. Thus, pepsin was added to the fraction to 2% (w/w) based on the IgG, and the mixture was subjected to digestion at 37°C for 24 hrs.The digested product was adjusted to a pH of 7.0 with a 2M Tris solution thereby to stop the reaction. The product was gel-filtrated on a Ultrogel™ AcA 44 column equilibrated with a 0.1M phosphate buffer solution (pH 7.0) to obtain F(ab') 2 fraction.The F(ab') 2 fraction was then dialyzed against a 0.1M phosphate buffer solution (pH 6.0) containing 5mM ethylenediamine tetraacetic acid (EDTA), and aminoethanethiol was added to a final concentration of 10mM to effect reduction at 37°C for 90 min. The product was gel-filtrated on a Ultrogel™ AcA 44 column equilibrated with a 0.1M phosphate buffer solution (pH 6.0) containing 5mM EDTA to obtain Fab' fraction. (2) Preparation of maleimide-labeled POD fraction Separately from the procedure as mentioned in (1) above, POD was labeled with a maleimide compound as follows. Thus, the POD was dissolved in a 0.1M phosphate buffer solution (pH 7.0) to 10 mg/ml and to the solution was added 25 moles, per mole of the POD, of N-(ε-maleimidocaproyloxy)succinimide as a solution in dimethylformamide (DMF) for reaction at 30°C for 30 min. The product was gel-filtrated on a Sephadex™ G-50 column equilibrated with a 0.1M phosphate buffer solution (pH 6.0) to obtain maleimide-labeled POD fraction. (3) Preparation of Fab'-POD conjugate fraction The fractions as prepared in (1) and (2) above were admixed so that equimolar amounts of Fab' and maleimide-labeled POD in the respective fractions were mixed. The mixture was then diluted with a 0.1M phosphate buffer solution (pH 6.0) containing 5mM EDTA to a final concentration, in respect of both Fab' and maleimide-labeled POD, of 100µM.After reaction at 4°C for 20 hrs. was added 10 moles per mole of Fab', of N-ethylmaleimide to block unreacted thiol groups. The product was gel-filtrated on a Ultrogel™ AcA 44 column equilibrated with a 0.1M phosphate buffer solution (pH 6.5) to obtain Fab'-POD conjugate fraction, to which 0.1% bovine serum albumin (BSA) and 0.001% chlorhexidine were added for storage at 4°C. (b) Preparation of monoclonal antibody-coated balls: According to the method of Ishikawa et al. as described in J. Immunoassay 4 , 209-327 (1983), purified monoclonal antibody obtained in Example 1(i) was dissolved in a 0.1M phosphate buffer solution (pH 7.5) containing 0.1% sodium azide to a concentration of 100 µg/ml. Polystyrene balls (6.5 mm in diameter, supplied by Precision Plastic Ball) were soaked therein and allowed to stand at 4°C for 24 hrs. After removal of the monoclonal antibody solution, the balls were washed with a 10mM phosphate buffer solution (pH 7.0) containing 0.1% BSA, 0.1% NaCl and 0.001% chlorhexidine and stored at 4°C. (c) Enzyme Immunoassay To prepare standard samples, the purified human prostromelysin obtained in Example 1(a) was dissolved in a 10mM phosphate buffer solution (pH 7.0) containing 0.1M sodium chloride and 1% BSA to prepare a 1280 ng/ml solution. The solution was subjected to serial dilution and a 50 µl portion was taken from each dilution. On the other hand, a 50 µl aliquot of serum from normal subjects, patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA) were used as test samples. Each of the samples mentioned above was placed in a test tube and dissolved in 300 µl of a 30mM phosphate buffer solution (pH 7.0) containing the Fab'-POD conjugate fraction (100 ng/ml) prepared in (a) above, 0.1M sodium chloride and 10mM EDTA. One monoclonal antibody-coated polystyrene ball prepared as described above was added into each of these test tubes and the mixture was allowed to stand at room temperature for one hr and then washed with a 5mM phosphate buffer solution (pH 7.0) containing 50mM sodium chloride. A 300 µl portion of 0.025% tetramethylbenzidine (substrate for POD) dissolved in a 0.1M acetate buffer solution (pH 5.5) containing 9% DMF, and then a 300 µl portion of 0.0075% acqueous hydrogen peroxide, were added and after the mixtures were allowed to stand at room temperature for 30 min a 1400 µl portion of 1.75N sulfuric acid were added to stop the reaction. The absorbance at wavelength 450 nm of the liquid reaction mixtures was measured using a Shimazu Micro-Flow spectrophotometer (UV-730), and the concentration of human stromelysin corresponding to the absorbance of test sample was read from a standard curve prepared with the standard samples. The standard curve is shown in Fig. 1 which was obtained when IgG (clone 55-3G3) was used as the solid phase antibody and IgG (clone 55-2A4) as the labeled antibody. Quantitation of human stromelysin is possible also with other monoclonal antibody combinations, but the highest sensitivity was obtained with the above mentioned combination. Furthermore, as shown in Table 1, the resultant monoclonal antibodies are equipped with reactivity with both latent and active forms of stromelysin. In the above described sandwich assay systems, therefore, both latent and active forms of stromelysin in samples are quantitated simultaneously. On the other hand, since neither solid phase antibody nor labeled antibody reacts with collagenase or gelatinase as described in Example 1 (j), only stromelysin is specifically quantitated in the above described assay systems. As shown in Fig. 1, A 450 increases as the concentration of human stromelysin in standard samples increases, with the determination sensitivity being 20 ng per ml of sample. (d) Quantitation of stromelysin for patients with RA or OA In accordance with the enzyme immunoassay shown in (c) above, stromelysin in bloods from normal subjects, patients with RA and patients with OA was quantitated. A 50 µl aliquot of serum samples from normal subjects (9 samples), patients with RA (10 samples) and patients with OA (11 samples) were used to measure the concentration of stromelysin therein. The results are as shown in Table 2. Thus, the concentration of stromelysin (mean ± S.D.) in sera from normal subjects was 65.9 ± 20.3 ng/ml. On the other hand, the concentration of stromelysin (mean ± S.D.) in sera from patients with RA was 731.8 ± 369.4 ng/ml, significantly higher than that in sera from normal subjects, whereas the concentration of stromelysin in sera from patients with OA was 84.3 ± 49.6 ng/ml, not significantly different from that in sera from normal subjects. As samples for carrying out the diagnosis as described above, there may be used bloods or synovial fluids, or where appropriate stromelysin-containing samples available from live body. Furthermore, stromelysin in synovial fluids from patients with RA and with OA was measured. Thus, the concentration of stromelysin was measured for synovial samples from patients with RA (9 samples) and with OA (10 samples). When the synovial fluids each of 50 µl were used, the absorbance (A 450 ) exceeded the range readable from the standard curve, so that the synovial fluids were diluted 10 - 100 times before being subjected to the measurement. The results were as shown in Table 3. Thus, the concentration of stromelysin (mean ± S.D.) in synovial fluids from patients with RA was 49257 ± 23267 ng/ml, significantly higher than that for patients with OA (10097 ± 640 ng/ml). Reactivity with Clone No. Subclass Latent Stromelysin Active Stromelysin 55-1F5 IgG1/κ + + 55-2A4 IgG1/κ + + 55-3G3 IgG1/κ + + 55-6F10 IgG2a/κ + + 55-7C10 IgG2b/κ + + 55-8A3 IgG2a/κ + + 55-9A9 IgG1/κ + + 55-10H2 IgG1/κ + + 55-11F1 IgG2b/κ + + 55-14G6 IgG1/κ + + 55-16D5 IgG1/κ + + 55-18D2 IgG1/κ + + 55-19D5 IgG1/κ + + 55-20A2 IgG1/κ + + Sera from normal subjects Sera from patients with RA Sera from patients with OA Sample No. Concentration of Stromelysin (ng/ml) Sample No. Concentration of Stromelysin (ng/ml) Sample No. Concentration of Stromelysin (ng/ml) 1 42 1 470 1 170 2 66 2 650 2 81 3 53 3 1500 3 20 4 66 4 790 4 34 5 42 5 118 8 75 6 64 6 500 6 113 7 68 7 570 7 156 8 87 8 960 8 70 9 105 9 940 9 98 10 820 10 20 11 90 Mean 65.9 Mean 731.8 Mean 84.3 S.D. 20.3 S.D. 369.4 S.D. 49.6 Synovial fluids from patients with RA Synovial fluids from patients with OA Sample No. Concentration of Stromelysin (ng/ml) Sample No. Concentration of Stromelysin (ng/ml) 1 22050 1 2478 2 58800 2 19320 3 69300 3 6405 4 79800 4 5040 5 4200 5 10080 6 56280 6 21000 7 46200 7 13440 8 57960 8 11760 9 48724 9 8505 10 2940 Mean 49257 Mean 10097 S.D. 23267 S.D. 6402 BRIEF DESCRIPTION DRAWING Fig. 1 shows the standard curve obtained in Example 3(c), i.e. the standard curve for human stromelysin prepared by way of the one-step sandwich method with IgG (clone 55-3G3) as the solid phase antibody and IgG (clone 55-2A4) as the labeled antibody.

Claims: Mouse-derived anti-human stromelysin monoclonal antibody obtainable from Hybridoma 55-2A4, FERM P-12303. Mouse-derived anti-human stromelysin monoclonal antibody obtainable from Hybridoma 55-3G3, FERM P-12304. Hybridoma 55-2A4, FERM P-12303 producing mouse-derived anti-human stromelysin monoclonal antibody. Hybridoma 55-3G3, FERM P-12304 producing mouse-derived anti-human stromelysin monoclonal antibody. An enzyme immunoassay for human stromelysin characterized in that the sum of the amount of latent stromelysin and the amount of active stromelysin is determined by the sandwich method using a combination of two monoclonal antibodies as claimed in any one of claims 1 or 2 which specifically bind to their respective different antigenic determinants of human stromelysin. A method for the diagnosis of rheumatoid arthritis comprising measuring by way of the enzyme immunoassay as claimed in claim 5 the amount of human stromelysin present in a sample as the sum of the amount of latent stromelysin and that of active stromelysin and comparing the measured amount with that for corresponding samples from normal subjects. A method for the diagnosis of rheumatoid arthritis as claimed in claim 6, wherein the sample is a sample of human blood or human synovial fluid. A method for the diagnosis of rheumatoid arthritis comprising immunohistochemically detecting stromelysin in a sample of human synovial tissue, using the monoclonal antibodies as claimed in any one of claim 1 or 2.

Inventors: HAYAKAWA TARO, IWATA KAZUSHI, KODAMA SHUJI, KORIN YUMI, OKADA YASUNORI, SHINMEI MASAYOSHI, YOSHIDA SHINICHI, HAYAKAWA, TARO, IWATA, KAZUSHI, KODAMA, SHUJI, KORIN, YUMI, OKADA, YASUNORI, SHINMEI, MASAYOSHI, YOSHIDA, SHINICHI
Applicants: FUJI YAKUHIN KOGYO KK, FUJI YAKUHIN KOGYO KABUSHIKI KAISHA
Application year: 1992
Main classification: C12P21
IPC codes: G01N33, C07K19, C12R1, C07K16, C12N5, C12N9, C12N15, C12P21