Collagen antibodies in juvenile arthritis and adult rheumatoid arthritis: differences in levels and type-specificity.

Antibodies to both native and denatured type II collagen were measured in the serum of 63 patients with juvenile onset arthritis (JA) and in 67 patients with adult onset rheumatoid arthritis (RA). Levels of antibodies in the 2 groups were compared with antibody levels in 30 healthy adult controls, and in 20 children with nonrheumatic diseases. Antibodies to denatured and native collagen were increased in RA but not in JA. There was no apparent difference between the collagen antibody levels in any of the 3 subgroups of JA, pauciarticular, polyarticular or systemic onset disease. Antibodies to denatured collagen were not type specific, and reacted similarly with type I and type II collagens, but antibodies to native collagen were much more specific, and most reacted more strongly on type II collagen than on type I collagen. Our results, unlike those in previous reports, imply that antibodies to collagen are infrequent in JA and hence cannot be implicated in the pathogenesis of that disease, which is in contrast to adult onset RA.