Fine specificity of serum anticollagen molecules in experimental immune synovitis.

Serum anticollagen antibodies to the native and denatured interstitial collagens were measured by solid phase radioimmunoassay (RIA) in a rabbit model of IgG-induced immune synovitis. Serum antibodies binding the native interstitial collagens and denatured type II collagen were observed in 100% of the animals tested (n = 6). Titerable antibodies to the alpha 1 (III) collagen polypeptide chain were observed in 83% of the animals, whereas serum antibodies to denatured type I collagen were observed in 33%. Inhibition studies showed that the observed serum anticollagen antibodies were conformationally dependent and collagen type specific. In addition these antibody populations varied in their affinities by as much as a factor of 2.81 for the specific substrates. Mean value of the average binding constants (Ka) for synovitis anticollagen antibodies binding native type II collagen was 5.47 X 10(6)mol; while the Ka determined for synovitis antibodies binding denatured type III collagen was 1.94 X 10(6)/mol. The data indicate that unique anticollagen antibody populations are expressed in the serum of animals with experimental IgG-induced chronic immune synovitis.