title: IFN-gamma-activated human alveolar macrophages inhibit the intracellular multiplication of Legionella pneumophila.
abstract: Human alveolar macrophages activated by human rIFN-gamma inhibit the intracellular multiplication of Legionella pneumophila, an intracellular bacterial pathogen and the agent of Legionnaires' disease. Activation of alveolar macrophages with IFN-gamma is dose dependent; significant inhibition of L. pneumophila multiplication (mean 1.60 +/- 0.20 logs) is achieved consistently with concentrations of IFN-gamma of greater than or equal to 2 x 10(-2) micrograms/ml (220 U/ml). Activation of alveolar macrophages is also time dependent. In macrophages treated continuously after explantation, macrophages infected at 48 to 96 h after explantation are more inhibitory than macrophages infected at 24 h after explantation. In macrophages not treated continuously after explantation but treated for various lengths of time before infection, the longer their exposure to IFN-gamma before infection, the greater the inhibition of L. pneumophila multiplication (96 greater than 72 greater than 48 greater than 24 h). IFN-gamma-activated alveolar macrophages exhibit morphologic signs of activation, including increased size, spreading, and aggregation. This paper demonstrates that a human resident macrophage can be activated with IFN-gamma such that it exhibits enhanced antimicrobial activity against a relevant pathogen.
mesh_terms: D000328:Adult; D001826:Body Fluids / Q000276:immunology*; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects; D007371:Interferon-gamma / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000276:immunology* / Q000382:microbiology; D007875:Legionella / Q000254:growth & development*; D007877:Legionnaires' Disease / Q000276:immunology / Q000382:microbiology; D008262:Macrophage Activation / Q000187:drug effects*; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D011650:Pulmonary Alveoli / Q000166:cytology; D013997:Time Factors
chemical_list: D007371:Interferon-gamma