Antibodies to type II collagen in early rheumatoid arthritis.

Antibodies to native and denatured type II collagen were investigated in a group of 79 patients with rheumatoid arthritis (RA) of disease duration less than 12 months (median 8 months; range 3-12 months). Using a solid-phase ELISA to measure these antibodies, the incidence of patients with levels above the upper limit of normal (mean of normal plus 3 SD) was low as compared to previous findings in patients with established disease. The majority of positive sera contained small amounts of IgM antibodies to denatured type II collagen whilst a few had IgG antibodies to native and denatured type II collagen. These findings suggest that the production of high levels of serum anti-type II collagen antibodies in patients with RA is a secondary phenomenon, which may exacerbate the disease rather than be a primary cause of disease.