INDIRECT STIMULATORY EFFECTS OF MURINE INTERLEUKIN-12 ON IN-VITRO PRODUCTION OF NITRIC-OXIDE BY MOUSE PERITONEAL-CELLS

The effect of murine interleukin-12 (IL-12) on L-arginine-dependent bi osynthesis of nitric oxide (NO) by mouse peritoneal cells was evaluate d. Interleukin-12 was found to trigger considerably enhanced productio n of NO in a dose-dependent manner. Antibody neutralization studies in dicated that the effect of IL-12 was mediated by IFN-gamma without app arent participation of TNF-alpha. Synergistic effects of IL-12 plus li popolysaccharide (LPS) were also observed. Our data thus provide evide nce that IL-12 is a powerful but indirect modulator of NO formation. T hese findings may contribute to the better understanding of various bi ologic effects of IL-12.