CD4+ suppressor cells differentially affect the production of IFN-gamma by effector cells of experimental autoimmune encephalomyelitis

Spleen cells from rats that have recovered from experimental autoimmune encephalomyelitis (EAE) suppress the production of IFN-gamma by effector T cells of EAE in an Ag-specific manner. These postrecovery suppressor cells also inhibit EAE in vivo. Fractionation of the postrecovery suppressor spleen cells on nylon wool and OX-8 coated plates yields a nylon wool-adherent CD4+ suppressor cell population that, when cocultured with effector T cells, suppresses IFN-gamma production by these effector cells. In contrast, the nylon wool-adherent, CD4+ postrecovery suppressor cell population fails to inhibit the production of IL-2 by the effector T cells. In further experiments, the effector T cell population was depleted of CD8+ cells and cocultured with the nylon wool-adherent, CD4+ postrecovery suppressor cells, and the supernatants were assayed for IFN-gamma and IL-2. IFN-gamma production was inhibited in these cultures but IL-2 production was not inhibited. Irradiated effector T cells were cocultured with CD4+ postrecovery suppressor cells, without myelin basic protein, in an effort to determine whether the mechanism of differential lymphokine suppression involved an anti-idiotypic response against effector T cells. No IL-2 was produced, indicating that there was no CD4+ suppressor cell mediated anti-idiotypic response against effector T cells. These studies suggest that the suppressor cell is a nylon wool adherent, CD4+ T cell that functions to down-regulate EAE effector T cells by differential inhibition of lymphokine production.