Anti-proliferative effect of IFN-gamma in immune regulation. I. IFN-gamma inhibits the proliferation of Th2 but not Th1 murine helper T lymphocyte clones.

A biphasic dose-response curve was observed when the IL-1-dependent HTL clone D10 was exposed to IL-1 plus supernatants from some activated T cell clones but not others. The active component that inhibited proliferation at high concentrations of these supernatants appeared to be IFN-gamma based on the following findings: 1) the biphasic pattern of responsiveness correlated with the presence of IFN-gamma in the supernatants; 2) an anti-IFN-gamma mAb augmented the proliferation of D10 cells to these supernatants; 3) rIFN-gamma inhibited profoundly the response of D10 cells stimulated with rIL-1 plus supernatant from activated D10 cells or with rIL-1 plus rIL-4; 4) the response of D10 cells to rIL-1 plus rIL-2 also was inhibited by rIFN-gamma, although to a lesser extent. The proliferation of an additional Th2 clone stimulated with rIL-1 plus rIL-4 or rIL-2 also was inhibited by rIFN-gamma, implicating IFN-gamma as an inhibitory lymphokine for Th2 cells in general. rIFN-gamma did not affect the proliferation of two Th1 clones, nor did it affect the proliferation of an unconventional HTL clone which produces both IL-4 and IFN-gamma and proliferates in response to IL-2 or IL-4 in an IL-1-independent fashion. The proliferation of D10 cells stimulated by Ag or by immobilized anti-CD3 antibody also was blocked by rIFN-gamma, whereas IL-4 production in response to these stimuli was unaffected, indicating that proliferation and not general cell function was specifically inhibited. Collectively, these data implicate IFN-gamma as a suppressive factor for the proliferation of the subset of HTL designated Th2, and suggest that the relative amounts of the various lymphokines present during an immune response may direct which T cell types increase in number.