Anti-collagen antibodies in sera from rheumatoid arthritis patients.

Anti-cartilage antibodies, demonstrable by immunofluorescence, were found in 3.3% of rheumatoid arthritis patients. In most of these patients antibodies to type II collagen were detected. In specificity studies on these anti-collagen antibodies, they appeared to be type specific, showing no reaction with collagen types I and III. Denatured type II collagen reacted much less well than native type II, but isolated peptides from different regions of the collagen molecule were differentiated by individual sera. Removal of the glycoside side chains from native type II collagen had no effect on its antigenicity. The findings suggest that these patients produce highly specific antibodies which react with the triple helix of type II collagen.