Collagen-induced arthritis--use of the direct and indirect haemolytic plaque-assay to study the humoral response to collagen.

Using both the direct and indirect haemolytic plaque assay, lymphocytes secreting antibodies to native type II collagen could be detected in the lymph nodes, spleen and blood of collagen-immunised rats. Sprague-Dawley, but not Alderley Park, strain rats showed clear differences in the number of plaque-forming cells in the lymph nodes between arthritic and non-arthritic rats. Differences also occurred between these strains in their response to the production of indirect plaques. The presence of native or denatured type II collage, but not type I collagen, was necessary to increase or maintain, in vitro, the lymphocytes producing anti-collagen antibody and the increase could be inhibited by serum from immunised rats or by colchicine.