To determine the effect of FTY720 on the development of autoimmune arthritis, DR1 Tg mice immunized with CII/CFA were treated with 1 mg/kg or 0.2 mg/kg of FTY720 every 3 days for a total of nine treatments over 3 weeks, and arthritis incidence and severity were evaluated. This evidence concerns the gene DR1 and arthritic joint disease.