title: Bacillus Calmette-Guérin-activated murine macrophages kill syngeneic melanoma cells under strict anaerobic conditions.
abstract: We have studied the spontaneous killing of B5(59) melanoma cells by Bacillus Calmette-Guérin (BCG)-elicited macrophages under strictly anaerobic conditions to investigate the role of oxygen in macrophage-mediated cytotoxicity. The number of melanoma cells capable of forming colonies after aerobic or anaerobic incubation with BCG-macrophages was used as the index of cytotoxicity. The BCG-macrophages killed melanoma cells regardless of the amount of oxygen present. The killing observed was proportional to the ratio of effector cells added; a ratio of 25:1 effector to target cells was required to achieve nearly 90% cytotoxicity both aerobically and anaerobically. This cytotoxicity was not dependent on a diffusible macrophage product nor on alteration of the medium by macrophages, since tumor cells incubated in the same culture medium, but not in contact with a mixed population of tumor cells and macrophages, were not killed. These results also indicated that macrophage-mediated cytotoxicity was dependent on macrophage-tumor cell contact. The mechanism responsible for the oxygen-independent cytotoxicity is unknown at present.
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D001500:BCG Vaccine / Q000494:pharmacology*; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004351:Drug Resistance; D005260:Female; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D008545:Melanoma / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010100:Oxygen / Q000494:pharmacology
chemical_list: D001500:BCG Vaccine; D006861:Hydrogen Peroxide; D010100:Oxygen