Native type II collagen-induced arthritis in the rat. Studies of the humoral response to collagen at the cellular level.

In rats immunized with native type II collagen the number of lymphocytes secreting anti-type II collagen antibodies was enumerated in the lymph nodes using the direct hemolytic plaque assay. Arthritic rats had more lymphocytes, more plaque forming cells to native type II collagen and higher levels of serum IgM antibody to native type II collagen than nonarthritic rats. In vitro incubation of lymphocytes with native type II collagen before the plaque assay greatly increased the number of plaque forming cells from arthritic rats but not from nonarthritic rats. These findings suggest that arthritic rats had greater reactivity to native type II collagen and were less able to control the humoral response to collagen than were nonarthritic rats.