INTERLEUKIN-10 (IL-10) INHIBITS THE INDUCTION OF NITRIC-OXIDE SYNTHASE BY INTERFERON-GAMMA IN MURINE MACROPHAGES

A murine macrophage cell line, J774, expresses high levels of the enzyme nitric oxide synthase (NOS) and produces large amounts of nitric oxide (NO) when activated with recombinant interferon (IFN)-γ and a low concentration of LPS (10ng/ml). Both the expression of NOS and the production of NO were inhibited by recombinant IL-10 in a dose-dependent manner. The inhibition was effective only when the cells were pretreated with IL-10; addition of IL-10 at the same time or after IFN-γ activation was without effect. These results demonstrate that IL-10, a product of Th2 (helper T lymphocyte 2) cells, can antagonise the function of IFN-γ, a product of Thl cells, by modulating the mechanism of synthesis of nitric oxide in the macrophages. © 1992.