Estimation of serum anticollagen and the antibodies against chondrocyte membrane fraction: their clinical diagnostic significance in osteoarthritis.

The serum anticollagen antibodies to collagen types II, IX, and XI, as well as the antibody level to chondrocyte membrane extract were investigated in patients suffering from severe osteoarthritis (n = 86) in comparison with patients free of primary arthritis (n = 33) and with control healthy patients (n = 44), respectively. Isolation and purification of cartilage antigens and their relevance to ELISA reaction have been outlined. Although the method for anticollagen antibodies to types IX and XI was more sensitive than that of type II, its sensitivity was very low (52%). The determination of the specific IgG fraction by affinity chromatography seemed to be more sensitive: in osteoarthritic patients the percentage of the "arthritogen" IgG rose to 10% of the total IgG. The determination of antibody level against chondrocyte membrane extract was adapted to human diagnostic purposes. In osteoarthritic patients the serum antibody level was significantly higher than in healthy controls. The specificity of this new test was proved by the facts that: (a) only the collagen-binding fraction of the membrane extract reacts with the patient's sera; (b) the ELISA reaction could be totally inhibited by the antigen; (c) patients suffering from noninflammatory joint diseases were characterized by low antibody levels.

The diagnostic significance of autoantibodies against cartilage components or their counterparts in destructive articular diseases.

In this work four different types of antibodies to collagens, membrane protein of chondrocytes (MP), cartilage matrix proteins (CMP) and heat shock proteins (HSP-s) were tested in order to find an available clinical laboratory method for diagnostic and monitoring purposes in patients suffering from osteoarthritis. From the point of view of diagnostic efficiency, the estimation of antibody level to MP seemed to be the best and as a supplementary method the determination of rheuma factor was recommended. The anticollagen antibody estimation is less sensitive, anti CMP antibodies are not detectable. In spite of immunological crossreaction between HSP and cartilage matrix component the antibody level against HSP has no correlation with osteoarthritis. The appearance of humoral reaction, antibodies against different cartilage specific collagens and chondrocyte membrane proteins, is an epiphenomenon, however as the supposed immune complexes, trapped in a cartilage, play an important role in the damage of cartilage which may explain the self-perpetuating and chronic nature of cartilage degradation on osteoarthritis.

The clinical diagnostic significance of serum antichondrocyte membrane antibodies in osteoarthritis.

In osteoarthritic patients significantly elevated level of antibodies against human chondrocyte membrane extract was found by double solid phase ELISA which seemed to be more specific for the disease than the antibody level of collagen types II, IX and XI. Altogether 86 patients with a mean age of 53.6 years and a ratio of 25% men and 75% women suffering from severe hip joint osteoarthritis were studied in comparison with 44 control persons with a mean age of 35.8 years and identical sex distribution. The specificity of reacting antibodies was proved partly by inhibition test and partly by the fact that the ELISA reaction could be produced only by proteins of the membrane extract bound to collagen (II) after affinity chromatography. The diagnostic importance of the methods is striking, in view of the lack of any other objective laboratory tests for the disease.