W e have used a murine model of organ-specific autoimmunity to characterize therapeutic modalities capable of down-regulating the cellular limb of the autoimmune response. Murine interstitial nephritis is an autoimmune disease mediated by tubular antigen-specific CD8+ nephritogenic effector T cells which are delayed-type hypersensitivity (DTH) reactive and cytotoxic to renal epithelial cells. Previous studies have demonstrated that disease can be suppressed with experimentally induced populations of T cells (Ts1 and Ts2 cells) obtained after injection of tubular antigen-coupled splenocytes into syngeneic mice. As the target of Ts2 is the CD8+ effector T cell, we have evaluated its effects on nephritogenic effector T cell clones isolated from diseased animals. Our studies demonstrate that soluble proteins expressed by Ts2 cells (TsF2) specifically abrogate the DTH, cytotoxic, and nephritogenic potential of M52 cells, although T cell receptor and IL-2 receptor expression are unchanged in these unresponsive M52 clones. TsF2-induced inhibition is dependent on new mRNA and protein synthesis. In a cytotoxic clone, M52.26, exposure to TsF2 induces expression of TGF-beta 1 which is, in turn, required for inhibition of cytotoxicity and nephritogenicity. Our studies are consistent with TGF-beta 1 behaving, at least in some T cells, as a nonspecific final effector of clone-specific suppression.