Regulation of human interleukin-2 and interferon-gamma gene expression by suppressor T lymphocytes

Concomitant with induction of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) gene expression in human tonsil cells, mitogenic stimulation induces a transient activation of cells able to effectively suppress expression of these genes. Induction of IL-2 and IFN-gamma genes largely precedes appearance of suppressor cell activity, allowing expression of both genes to occur before strong down-regulation is exerted by activated suppressor cells. Suppressive activity induced in one cell population can inhibit IL-2 and IFN-gamma gene expression in another population from the same donor. The distinct nature of suppressor cells is supported by the absence of down-regulation of IL-2 gene expression in a helper cell line, MLA-144; yet, in these cells, negative control can be expressed when active suppressor cells are introduced. Our findings support the concept that actual levels of IL-2 and IFN-gamma gene activity are regulated to a large extent by the differential kinetics of activation of suppressor cells on one hand and of cells expressing the IL-2 and IFN-gamma genes on the other.