Cytokine interactions in experimental cutaneous leishmaniasis. II. Endogenous tumor necrosis factor-alpha production by macrophages is induced by the synergistic action of interferon (IFN)-gamma and interleukin (IL) 4 and accounts for the antiparasitic effect mediated by IFN-gamma and IL 4.
Tumor necrosis factor-alpha (TNF-alpha) strongly activates murine peritoneal macrophages (M phi) for killing of amastigotes from Leishmania major in the presence of low amounts of interferon-gamma (IFN-gamma). Recently, we found that IFN-gamma and interleukin 4 (IL 4) also synergistically enhance the antileishmanial potential of M phi. In this report, evidence is provided that the synergism of IFN-gamma and IL 4 is based on the ability of the lymphokines to induce the endogenous production of TNF-alpha. First, both IFN-gamma and IL 4 as single agents and in combination were potent inducers of TNF-alpha production by M phi infected with L. major amastigotes. Second, the synergistic effect of IFN-gamma and IL 4 on parasite killing by M phi strongly correlated with their synergistic effect on the release of TNF-alpha. Third, the IFN-gamma/IL 4-mediated parasite elimination was completely abrogated not only in the presence of antibodies to IFN-gamma and IL 4, but also with an antibody specific for TNF-alpha. Consistent with the conclusion that endogenously produced TNF-alpha accounts for the synergism of IL 4 with IFN-gamma is the finding that N omega-monomethyl-L-arginine, an inhibitor of the L-arginine-dependent generation of microbicidal nitrogen intermediates, totally blocked the M phi activation induced by IFN-gamma combined with IL 4 as well as by IFN-gamma combined with TNF-alpha. These results underline the complex interplay of cytokines derived from lymphocytes and M phi and the role of TNF-alpha as pivotal factor for the induction of antileishmanial effector functions.
Stenger
S
S
Institute of Clinical Microbiology, University of Erlangen, FRG.
Solbach
W
W
Röllinghoff
M
M
Bogdan
C
C
D000818:Animals; D004357:Drug Synergism; D005260:Female; D007371:Interferon-gamma / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D007895:Leishmania tropica / Q000187:drug effects*; D007896:Leishmaniasis / Q000378:metabolism / Q000628:therapy; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; D007371:Interferon-gamma