Incidence of antibodies to native and denatured cartilage collagens (types II, IX, and XI) and to type I collagen in rheumatoid arthritis.

The frequencies of antibodies to the cartilage type IX and XI collagens and to type I collagen were determined in 188 patients with rheumatoid arthritis, of whom 76 were positive for antibodies to native type II collagen. A higher proportion of patients with antibodies to native type II collagen had antibodies to these other collagens, but about one third of patients without antibodies to native type II collagen had antibodies to one or more denatured collagens. The patterns of antibodies present in individual sera suggested that there was a selective response to the collagens in an individual patient. The incidence of patients having antibodies to these native and denatured collagens in a random group of patients with rheumatoid arthritis was calculated.