Effect of glycosaminoglycans on the detection of antibodies to collagen in synovial fluid.

Antibodies to collagen in the synovial fluid of RA patients were determined by radioimmuno assay using 14-C-labeled collagen and by passive hemagglutination with collagen coated erythrocytes. The effect of various glycosaminoglycans, possibly present in synovial fluid, on these two assays was investigated. None of the glycosaminoglycan preparations tested significantly changed either antibody titers or the amount of 14-C-radioactivity precipitated in radioimmunoassay. Digestion of the synovial fluid with chondroitinase ABC likewise had no effect on the results. It is therefore concluded that the glycosaminoglycans present in synovial fluid do not interact with native or denatured collagen under the experimental conditions existing in the determination of antibodies to collagen.