title: Bidirectional effects of IFN-gamma on growth of Mycobacterium avium complex in murine peritoneal macrophages.
abstract: The effects of macrophage stimulation with interferon-gamma (IFN-gamma) before or after infection on the intracellular growth of Mycobacterium avium complex (MAC) were investigated. Treatment of murine peritoneal macrophages before infection with IFN-gamma (50 U/ml) for 24 h and 48 h, but not for 72 h, was associated with 41% and 52% significant MAC growth inhibition, respectively. NG-monomethyl-L-arginine (NMA) did not affect the preinfection antimycobacterial activity of IFN-gamma, thus indicating that nitric oxide was not involved in this phenomenon. In contrast, treatment of macrophages with IFN-gamma (50 U/ml) for 24 h and 48 h after infection was ineffective, whereas treatment for 72 h caused some MAC growth promotion. The use of NMA suppressed the IFN-gamma-mediated MAC growth, suggesting that nitric oxide may affect postinfection microbicidal function of macrophages. These results suggest that activation of macrophages with IFN-gamma before or after infection may direct the course of the infection and that nitric oxide may be detrimental more than beneficial for MAC-infected macrophages.
authors.affiliation: Department of Bioimmunotherapy, University of Texas M.D. Anderson Cancer Center, Houston, USA.
authors.forename: R
authors.initials: R
authors.lastname: Gomez-Flores
authors.forename: R
authors.initials: R
authors.lastname: Tamez-Guerra
authors.forename: S D
authors.initials: SD
authors.lastname: Tucker
authors.forename: R T
authors.initials: RT
authors.lastname: Mehta
mesh_terms: D000818:Animals; D007371:Interferon-gamma / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D008262:Macrophage Activation / Q000187:drug effects; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009162:Mycobacterium avium / Q000187:drug effects* / Q000254:growth & development / Q000276:immunology; D009573:Nitrites / Q000378:metabolism; D013997:Time Factors
chemical_list: D009573:Nitrites; D007371:Interferon-gamma