Prevention of relapse after chemotherapy in a chronic intracellular infection: mechanisms in experimental visceral leishmaniasis.
In visceral leishmaniasis, chemotherapy probably seldom eradicates all parasites in tissue macrophages; nevertheless, most T cell-intact patients show long-lasting clinical cure after treatment despite residual intracellular infection. To characterize prevention of posttreatment relapse, amphotericin B was used to kill approximately 90-95% of Leishmania donovani in livers of mice deficient in mechanisms of acquired antileishmanial resistance. Recrudescence subsequently developed 1) in animals deficient in both CD4 and CD8 T cells as well as CD40L-mediated T cell costimulation, but not in a) CD4 or CD8 cells alone, b) NK cell lytic activity, or c) ICAM-1-recruited monocytes; and 2) in mice deficient in IFN-gamma, but not in the IFN-gamma-inducing cytokines, a) IL-12, b) IL-12 and IL-23, or c) IL-18. Posttreatment recrudescence also did not develop in animals deficient in macrophage phagocyte NADPH oxidase (phox) or inducible NO synthase (iNOS) alone or, surprisingly, in those deficient in both phox and iNOS. Therefore, regulation of the intracellular replication of residual Leishmania donovani that escape chemotherapy evolves to a host mechanism distinguishable from initial acquired resistance at the T cell, cytokine, and macrophage levels. Posttreatment, either CD8 or CD4 cells can direct the response, IL-12 is not required, and iNOS and phox, the activated macrophage's primary IFN-gamma-inducible leishmanicidal pathways, both become dispensable.
Murray
Henry W
HW
Department of Medicine, Weill Medical College of Cornell University, New York, NY 10021, USA. hwmurray@med.cornell.edu
D000666:Amphotericin B / Q000627:therapeutic use; D000818:Animals; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D023201:CD40 Ligand / Q000235:genetics / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D045303:Cytochromes b / Q000172:deficiency / Q000235:genetics; D016207:Cytokines / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology; D007893:Leishmania donovani / Q000187:drug effects; D007898:Leishmaniasis, Visceral / Q000188:drug therapy* / Q000276:immunology* / Q000469:parasitology; D008262:Macrophage Activation; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D009000:Monocytes / Q000276:immunology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D019001:Nitric Oxide Synthase / Q000172:deficiency / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012008:Recurrence
D000981:Antiprotozoal Agents; D016207:Cytokines; D008562:Membrane Glycoproteins; D018799:Intercellular Adhesion Molecule-1; D023201:CD40 Ligand; D000666:Amphotericin B; D045303:Cytochromes b; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases