Modulatory effect of bucillamine (SA96) on interleukin-1-and/or -2-induced proliferation of T lymphocytes

Bucillamine [SA96:N-(2-mercapto-2-methylpropanoyl)-L-cysteine], a synthetic SH compound, has recently been developed as remission-inducing agent for rheumatoid arthritis (RA), and its clinical usefulness for RA has been proved in Japan. Bucillamine suppressed the mitogen-induced proliferation of murine lymphocytes in vitro. The present study was undertaken to clarify the effect of bucillamine primarily on the release of interleukin (IL)-1 from monocytes and on the proliferation of T cells. Bucillamine significantly inhibited IL-1-induced thymocyte proliferation in a dose-dependent manner. And, bucillamine also inhibited IL-2-induced proliferation at the concentration of 1 x 10(-4) M, but augmented proliferation at the concentration of 1 x 10(-5) M. In contrast, D-penicillamine (an analogous SH compound to bucillamine) did not show any significant effect at similar concentrations.