Spontaneous rheumatoid-like arthritis in a line of mice sensitive to collagen-induced arthritis

Twenty-eight percent of 13-month-old male mice of the high antibody responder line of Biozzi's selection I (HI) spontaneously developed a long-lasting inflammatory arthritis. This disease was clinically and histologically similar to human rheumatoid arthritis. The synovium of joints and some tendons was hypertrophied, with thickening of the synovial cell layer and infiltration by polymorphonuclear and mononuclear leukocytes. In some cases, synovial pannus formation led to destructive damage of articular cartilage and bone. Rheumatoid factor and antinuclear, anti-DNA, and anti-type II collagen (CII) antibodies were often found in the sera of both arthritic mice and clinically normal littermates. The presence of CII autoantibodies in this line of mice suggests that a potentially harmful anti-CII T cell autoimmunity can also develop spontaneously and lead to joint damage. Moreover, HI mice are also susceptible to collagen-induced arthritis, while a closely related mouse line (HII) is resistant to both diseases. These data support the hypothesis that collagen-induced arthritis is pathogenetically related both to this spontaneous arthritis and to rheumatoid arthritis.