Effect of teleocidin on immune responses in vitro.

The effect of teleocidin, a new tumor promoter, on immune responses was studied in vitro using murine lymphocytes. Teleocidin had a mitogenic and a comitogenic activity on murine lymphocytes at doses of 1-1000 ng/ml. The responder cells to teleocidin stimulation were T cells. However, for the stimulation of T cells with teleocidin, Ia-positive macrophages were required as accessory cells. On the other hand, teleocidin had a suppressive activity at the same doses on the induction of hapten-reactive cytotoxic T cell response in vitro. All these results on mitogenic and immunosuppressive activity are similar to those obtained in a previous study on 12-O-tetradecanoyl phorbol-13-acetate. Thus, it is suggested that the role of tumor promoters during carcinogenesis is a potentiation of the growth of transformed cells and a suppression of the immune-surveillance mechanism.