Transforming growth factors beta 1 and beta 2: cytokines with identical immunosuppressive effects and a potential role in the regulation of autoimmune T cell function.

The transforming growth factors TGF-beta 1 and beta 2 are cytokines with pronounced effects on leukocyte growth and function. To evaluate a potential use of these factors as immunosuppressive agents, we compared the effects of TGF-beta 1 and beta 2 on autoimmune T cells in rat inflammatory central nervous system disease, experimental allergic encephalomyelitis (EAE). We observed that both factors strongly inhibited in vitro activation of autoimmune T cells, suppressed the accumulation of interleukin-2 mRNA and decreased the expression of rat T cell activation antigens. In addition, cyclical changes in susceptibility to TGF-beta was observed with T line cells. The modulation of in vitro T cell function is associated with a considerable suppression of encephalitogenic capacity of autoimmune T line cells. Thus, TGF-beta 1 and beta 2 might have physiologic importance in limiting local T lymphocyte proliferation and effector function in autoimmune disease.