INTERLEUKIN-12-STIMULATED AND INTERLEUKIN-2-STIMULATED RELEASE OF INTERFERON-GAMMA BY UTERINE CD56(++) LARGE GRANULAR LYMPHOCYTES IS AMPLIFIED BY DECIDUAL MACROPHAGES

Numerous studies have suggested that interferon-gamma (IFN-gamma) exhi bits an inhibitory effect on conceptus development during pregnancy, a nd recent investigations have shown that decidual CD56(+ +), CD16(-) l arge granular lymphocytes (LGL) contain mRNA for IFN-gamma. We have in vestigated the influence of exogenous interleukin-12 (IL-12) and inter leukin-2 (IL-2) on IFN-gamma secretion by cultivated LGL and macrophag es isolated from first trimester human decidua. The effect of decidual macrophages on IFN-gamma secretion by LGL was also assessed using co- incubation experiments. Neither IL-12 nor IL-2 stimulated the secretio n of IFN-gamma by decidual macrophages. IL-12 alone, but not IL-2 alon e, stimulated the release of IFN-gamma by LGL. However, IL-2 acted syn ergistically with IL-12 to enhance the release of IFN-gamma by LGL. Un stimulated and IL-12- and IL-2-stimulated LGL incubated with macrophag es exhibited a marked increase in secretion of IFN-gamma compared to t hose in monoculture. This effect was also seen when the LGL and macrop hages were separated by a semi-permeable membrane. The results suggest that interactions between decidual LGL and macrophages, possibly medi ated by soluble factors, could play a role in regulating IFN-gamma sec retion at the materno-fetal interface and thus contribute to the contr ol of invasion by the trophoblast.