Suppressor T-cell hybridomas specific for the synthetic polypeptide antigen L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) release TsF spontaneously and are not dependent on exogenous sources of lymphokines for their growth. IL-2 has no effect on the cell growth of these hybridomas and little overall effect is observed on protein biosynthesis. Nevertheless, the addition of IL-2 to one of these hybridomas (762 B3.7), leads to a substantial increase in suppressor factor (TsF2) production as measured by both bioactivity and direct analysis of 35S-methionine incorporation into TsF2. Treatment of the TsF2 producing hybridoma with phorbol myristate acetate (PMA) causes an increase in the level of IL-2 receptor expression in this hybridoma and enhances the effects of IL-2 on the biosynthesis of TsF2. These data suggest that in addition to its growth promoting properties, IL-2 may provide a signal that triggers suppressor cells to produce antigen specific suppressor factors.