Leishmania major: infection of human monocytes induces expression of IL-8 and MCAF

Leishmania major, the causative agent of cutaneous leishmaniasis, is an intracellular parasite of monocytic cells. Leishmania lesions are characterized by recruitment of neutrophils, eosinophils, and blood monocytes. To clarify the mechanism of this cellular influx we examined the expression of IL-8 and MCAF, cytokines chemotactic for neutrophils and monocytes, respectively, in human monocytes infected by L. major. Supernatants of monocytes infected with L. major had chemotactic activity for neutrophils and monocytes that was neutralized by anti-IL-8 and anti-MCAF antibodies. Both IL-8 and MCAF mRNAs were induced within 1 hr of infection. Furthermore we showed that infection of monocytes with L. major induces IL-8 and MCAF but not the proinflammatory cytokines IL-1 beta and TNF alpha. These data suggest that the expression of chemokines may contribute to the cellular recruitment in Leishmania lesions.