Chemokine-induced leishmanicidal activity in murine macrophages via the generation of nitric oxide.

This study explored the role of the proinflammatory chemokines macrophage inflammatory protein (MIP)-1alpha and macrophage chemoattractant protein (MCP)-1 for development of antileishmanial activity. There was substantial inhibition in nitrite generation in Leishmania donovani-infected macrophages. A marked elevation of nitrite generation and induction of inducible nitric oxide (NO) synthase (iNOS) mRNA was found in chemokine-primed parasite-infected macrophages. Tumor necrosis factor-alpha, which is the priming signal for NO production, was also up-regulated under similar experimental conditions. The priming with chemokine inhibited the multiplication of L. donovani amastigotes within the intramacrophageal milieu. The antileishmanial effect of chemokines was almost completely abrogated when the macrophages were preincubated with l-N-monomethyl arginine, the specific inhibitor of iNOS. The results of this investigation suggest that the CC chemokines MIP-1alpha and MCP-1 orchestrate an antileishmanial armamentarium via the induction of an NO-mediated regulatory mechanism to control the intracellular growth and multiplication of the Leishmania protozoan.