Effect of a novel anti-rheumatic drug, TA-383, on type II collagen-induced arthritis--suppressive effect of TA-383 on interleukin 6 production.

We have evaluated the effect of a novel anti-rheumatic drug, cis-2-(4-chlorophenyl)-4,5-diphenyl-2-imidazoline hydrochloride (TA-383), on type II collagen (CII)-induced arthritis in DBA/1J mice. Treatment with TA-383 (0.4 mg/kg/day) from the day of immunization with CII strongly suppressed the arthritic responses. Increased serum interleukin 6 (IL-6) level was lowered in parallel with the effect. Effect of TA-383 on IL-6 production was examined in vitro. TA-383 inhibited the production of IL-6 by murine synovial fibroblasts stimulated with recombinant interleukin 1 (IL-1) beta in a dose-dependent manner (0.1-10 microM). Neither the general protein synthesis nor the expression of type I IL-1 receptor was affected by TA-383. The results show that TA-383 possesses an inhibitory activity on IL-6 generation and suggest that the effect may partly contribute to the anti-arthritic effect of TA-383.