title: Antagonistic effect of interferon-beta on the interferon-gamma-induced expression of Ia antigen in murine macrophages.
abstract: The cell surface expression of I region-associated (Ia) antigens by murine and human macrophages has been shown by investigators from a number of laboratories to be induced in a dose-dependent fashion by IFN-gamma, which is free of other lymphokines. The experiments described in this report demonstrate that fibroblast-derived IFN-beta exerts an antagonistic effect on IFN-gamma induced Ia expression in murine macrophages. Simultaneous addition of IFN-beta and IFN-gamma to peritoneal exudate macrophages results in decreased Ia expression when compared with macrophages treated with IFN-gamma only. Different sources of highly purified IFN-beta, as well as a recombinant human IFN-alpha (A/D Bgl; shown previously to be as active as IFN-beta in several other murine systems) acted in a similar antagonistic fashion to IFN-gamma-induced Ia induction. The down-regulation of Ia expression by IFN-beta is dose-dependent over a concentration range up to 100 U/ml. Time-course experiments indicated that for IFN-beta to down-regulate IFN-gamma-induced Ia, it had to be present either before stimulation with IFN-gamma or during the first 24 hr of simultaneous stimulation. Further experiments in which a highly specific antibody against IFN-alpha/beta was added to the cultures confirmed the findings of the time-course experiments. Inhibitors of the arachidonic acid pathway failed to reverse the effect of IFN-beta to reduce Ia antigen expression, which suggests that this inhibition is not prostaglandin mediated. Thus, these findings support a role for type I IFN as naturally occurring substances that negatively regulate the expression of class II molecules.
mesh_terms: D000818:Animals; D004274:DNA, Recombinant; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007213:Indomethacin / Q000494:pharmacology; D007370:Interferon Type I / Q000494:pharmacology*; D007371:Interferon-gamma / Q000037:antagonists & inhibitors*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D013997:Time Factors
chemical_list: D004274:DNA, Recombinant; D000949:Histocompatibility Antigens Class II; D007370:Interferon Type I; D007371:Interferon-gamma; D007213:Indomethacin