Involvement of interferon-gamma and tumor necrosis factor-alpha in host defense against Rhodococcus equi.
Rhodococcus equi is a facultative, intracellular, gram-positive coccobacillus increasingly reported as an opportunistic pathogen in AIDS patients. In vitro, splenic cells of noninfected euthymic mice produced tumor necrosis factor-alpha (TNF alpha) in greater amounts when incubated with live R. equi rather than with killed bacteria. In vivo, interferon-gamma (IFN-gamma) and TNF alpha serum levels of infected euthymic mice remained below the level of detectability. Treatment of infected nude mice, which developed chronic infection, with discontinuous injections of IFN-gamma, TNF alpha, or both did not decrease bacterial colony-forming units in liver, spleen, or lungs. However, treatment of infected euthymic mice, which cured a R. equi inoculum within 3 weeks, with anti-IFN-gamma or anti-TNF alpha antibodies (or both) significantly increased tissue colony counts. These data argue that, in this murine model, endogenous IFN-gamma and TNF alpha are involved in the cell-mediated immunologic response against R. equi infection.
Department of Microbiology, Paris-Ouest Medical School, Paris V University, Garches, France.
P
P
Nordmann
E
E
Ronco
M
M
Guenounou
D000193:Actinomycetales Infections / Q000276:immunology*; D000818:Animals; D005260:Female; D007371:Interferon-gamma / Q000276:immunology*; D051379:Mice; D008819:Mice, Nude; D016929:Rhodococcus equi / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma