title: Tumor necrosis factor-alpha-dependent production of reactive nitrogen intermediates mediates IFN-gamma plus IL-2-induced murine macrophage tumoricidal activity.
abstract: We have previously established that IFN-gamma plus IL-2 induces murine macrophage tumoricidal activity. The purpose of this study was to identify the effector molecules that account for the IFN-gamma plus IL-2-induced macrophage cytotoxicity against P815 mastocytoma cells. ANA-1 macrophages and normal thioglycollate-elicited mouse peritoneal macrophages produced little or no detectable nitrite (NO2-) after incubation with IFN-gamma alone or IL-2 alone; however, IL-2 synergized with IFN-gamma for the production of NO2-. IFN-gamma plus IL-2 did not induce NO2- production or tumoricidal activity in ANA-1 macrophages that were cultured in medium devoid of L-arginine or in ANA-1 macrophages that were incubated with NG-monomethyl-L-arginine. As observed previously with ANA-1 macrophage tumoricidal activity, IL-4 inhibited IFN-gamma plus IL-2-induced, but not IFN-gamma plus LPS-induced, NO2- production. IL-4 also selectively decreased the ability of IFN-gamma and/or IL-2 to augment TNF-alpha mRNA expression in ANA-1 macrophages. Lastly, incubation of ANA-1 macrophages with anti-TNF mAb selectively inhibited the ability of IFN-gamma plus IL-2 to induce NO2- production and tumoricidal activity. These results indicate that IFN-gamma plus IL-2-induced tumoricidal activity is dependent upon the metabolism of L-arginine to reactive nitrogen intermediates, and they establish a role for TNF-alpha as a required intermediate for IL-2-dependent NO2- production and tumoricidal activity.
authors.affiliation: Laboratory of Molecular Immunoregulation, National Cancer Institute-Frederick Cancer Research and Development Center, National Institutes of Health, MD 21702-1201.
authors.forename: G W
authors.initials: GW
authors.lastname: Cox
authors.forename: G
authors.initials: G
authors.lastname: Melillo
authors.forename: U
authors.initials: U
authors.lastname: Chattopadhyay
authors.forename: D
authors.initials: D
authors.lastname: Mullet
authors.forename: R H
authors.initials: RH
authors.lastname: Fertel
authors.forename: L
authors.initials: L
authors.lastname: Varesio
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D007371:Interferon-gamma / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology; D008070:Lipopolysaccharides; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D012515:Mast-Cell Sarcoma / Q000276:immunology; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000494:pharmacology*
chemical_list: D007376:Interleukin-2; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; D009569:Nitric Oxide; D007371:Interferon-gamma; D001120:Arginine