Regulation of cytokine production by exogenous nitric oxide in murine splenocyte and peritoneal macrophage

Nitric oxide (NO), products of activated macrophages, have a great impact o n the regulation of cytokine production. The role of NO in non-specific hos t cells is commonly accepted. On the contrary, its role as an immune-regula tory molecule is still controversial. In this study, we have investigated t he effect of NO on the production of cytokines from murine splenocytes and macrophages. S-nitroso-L-glutathione inhibited the release of both interfer one-gamma and interleukin-2 produced by Th1 cells and tumor necrosis factor -alpha and interleukin-1 beta produced by macrophages, but did not affect t he release of interleukin-4 and interleukin-10 produced by Th2 cells. These results suggest that NO exerts a down-regulatory effect on the secretion o f cytokines from Th1 cells and macrophages which are implicated in immune r esponse. Thus, NO may have an important role as an immuno-modulatory as wel l as effector molecule in the immune system.