Native type II collagen-induced arthritis in the rat. II. Relationship between the humoral immune response to native type II collagen and arthritis.

The onset of arthritis in Sprague-Dawley rats occurred between 10-13 days after intradermal injection of collagen when serum IgM and IgG antibody levels to native type II collagen had reached high levels. Although arthritis could be induced in rats immunized with 25-500 microgram native type II collagen in incomplete Freund's adjuvant, higher serum IgM and IgG antibody levels to native type II collagen occurred in arthritic rather than non-arthritic rats irrespective of the immunizing dose of collagen. Studies in 3 different rat strains showed that higher serum antibody levels to native type II collagen were found in the strain with the highest incidence of arthritis. All these findings suggest that these antibodies are one essential for the induction and/or perpetuation of native type II collagen-induced arthritis.