OBJECTIVE: Immunization of rats with alpha-tropomyosin (TPM) led to arthritis, uveitis and dermatitis, typical features of Behçet's disease (BD). The present study characterizes the arthritic features of this animal model, not previously described. METHODS: Lewis rats were immunized with bovine alpha-TPM and another group of rats was treated with neutralizing anti- tumor necrosis factor-alpha (TNF-alpha) antibodies. RESULTS: Clinically more than 90% of the immunized rats developed severe acute arthritis 12 days after vaccination. Rats that were followed-up for 6 months had persistent inflammation of the leg joints. Histologic studies demonstrated predominant mononuclear infiltrations in the acute phase of arthritis; the chronic arthritic process resulted in cartilage and bone damage and abundant fibrosis which led to joint deformations. Male and female rats had a similar clinical course. Analysis of the splenocyte cytokine profile kinetics revealed a persistently high level of interferon-gamma (INF-gamma) and an increase in TNF-alpha secretion during the acute phase. Increasing levels of interleukin (IL)-10 heralded the decline in clinical arthritis. No IL-4 was detected. No arthritis was detected in the rats treated with anti-TNF-alpha antibodies. CONCLUSION: The data indicates that alpha-TPM serves as an autoantigen to induce acute and chronic destructive arthritis in rats. This model is a TNF-alpha dependent autoimmune disease, with a Th1 cytokine profile.