Induction of suppressor cells by staphylococcal enterotoxin B: identification of a suppressor cell circuit in the generation of suppressor-effector cells.

We have shown previously that staphylococcal enterotoxin B (SEB) has the capacity to non-specifically inhibit antibody responses in vitro through the induction of a suppressor cell population. In the present studies, an analysis of the cellular dynamics has shown that the generation of Lyt-1-2+ suppressor-effector cells is dependent on the initial activation by SEB of an Lyt-1+2- suppressor-inducer population. Co-culture experiments carried out in vitro suggest that the induction of the suppressor-effector population requires at least two signals: one signal is provided by the suppressor-inducer population, and the second signal is provided by SEB. Studies also show that the in vitro antibody response is suppressed when the suppressor cells are added as late as Day 4 of a 5-day culture. While the suppressor cell population activated early in the antibody response is Lyt-1-2+, depletion studies suggest that the population that acts late in an ongoing response bears the Lyt-1+2+ surface phenotype. The results demonstrate that at least three distinct SEB-induced T-cell populations are capable of participating in the suppression of the antibody response. The relationship between the generation of non-specific suppressor cells and the activation of antigen-specific cell circuits is discussed.