THE MACROPHAGE-ACTIVATING TETRAPEPTIDE TUFTSIN INDUCES NITRIC-OXIDE SYNTHESIS AND STIMULATES MURINE MACROPHAGES TO KILL LEISHMANIA PARASITES IN-VITRO

The macrophage-activating tetrapeptide tuftsin was able to activate, i n a dose-dependent manner, murine macrophages to express nitric oxide (NO) synthase and to produce NO. Tuftsin required lipopolysaccharides for the optimal induction of NO production and synergized with gamma i nterferon in the induction of NO synthesis. Tuftsin-dependent NO produ ction was sensitive to inhibition by dexamethasone and the NO synthase specific inhibitor L(G)N-monomethylarginine (L-NMMA). Murine peritone al macrophages activated by tuftsin were able to kill the amastigotes of the intracellular protozoan parasite Leishmania major in vitro.