Leishmania parasites and their ploys to disrupt macrophage activation

Leishmania are intracellular protozoan parasites of macrophages. At the cel lular level, the disease leishmaniasis involves the invasion of tissue macr ophages by the parasite, the avoidance of cellular killing mechanisms, and the subsequent intracellular replication of parasites, with the eventual sp read of the organisms to adjacent macrophages. This paper describes the pro cess by which Leishmania organisms invade macrophages, with an overview of some of the molecules involved in this process; the mechanisms available to macrophages that have the potential to restrict the growth of Leishmania w ithin them; and the ways that Leishmania and Leishmania-derived molecules c an modulate macrophage functions and circumvent leukocyte antimicrobial res ponses. (C) 2000 Lippincott Williams & Wilkins, Inc.