Direct activation of murine peritoneal macrophages for nitric oxide production and tumor cell killing by interferon-gamma.
Interferon-gamma (IFN-gamma) is known to prime macrophages for tumor cell lysis and nitric oxide (NO) production as measured by enhanced sensitivity to lipopolysaccharide (LPS). In the present study, the ability of IFN-gamma to directly activate peritoneal macrophages from C57BL/6 and Balb/c mice for tumor cytotoxicity and NO production was evaluated. Macrophage-mediated tumor cell killing was measured by an 18 h 51Cr release assay using P815 mastocytoma cells as targets. Concurrent NO production was measured as nitrite in the supernatants of macrophage cultures. Incubation of macrophages with IFN-gamma resulted in activation of macrophages for tumor cell lysis. IFN-gamma alone also activated macrophages for NO production under identical conditions. Addition of LPS along with IFN-gamma resulted in synergism in the activation of macrophages for both cytolysis and NO production. LPS contamination of the IFN-gamma preparation was absent as evidenced by the following criteria: (1) the IFN-gamma preparation as well as the reagents used were shown to be free of LPS contamination based on LAL endotoxin tests (sensitivity 25 pg/ml), (2) the ability of IFN-gamma to activated macrophages was not abrogated by prior treatment of the cytokine with polymyxin B, whereas the effect of LPS was inhibited (70-100%) under similar conditions, (3) pretreatment of the IFN-gamma preparation with a specific endotoxin neutralizing protein did not abrogate the ability of IFN-gamma to induce macrophage activation, and (4) heat treatment of solutions containing IFN-gamma alone or IFN-gamma+LPS abolished only the effect of IFN-gamma, not that of LPS.(ABSTRACT TRUNCATED AT 250 WORDS)
Dileepan
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KN
Department of Medicine, University of Kansas Medical Center, Kansas City 66160-7317, USA.
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Li
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Stechschulte
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D000818:Animals; D002364:Caseins / Q000494:pharmacology; D003601:Cytotoxicity Tests, Immunologic; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D007371:Interferon-gamma / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000096:biosynthesis*; D010446:Peptide Fragments / Q000494:pharmacology; D010461:Peptones / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D011994:Recombinant Proteins; D013696:Temperature; D014407:Tumor Cells, Cultured
D002364:Caseins; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D010461:Peptones; D011994:Recombinant Proteins; C018135:proteose-peptone; D009569:Nitric Oxide; D007371:Interferon-gamma; D011112:Polymyxin B