[Cytolytic activity of macrophages from 5 strains of rats]

Resident peritoneal macrophages from 5 conventional or pathogen-free rat strains, without in vivo or in vitro stimulation, were generally tumoricidal in vitro against tumor cells: this spontaneous cytolysis rate varied from one rat to another but was significantly different according to the strains. Endotoxins induced or increased macrophage-mediated cytolysis from BDIX, Wistar and Sprague-Dawley rats; they were without effect on those from Long-Evans rats and their effect was irregular on Sprague-Dawley Hairless macrophages. Endotoxin effect depended on natural cytolysis intensity.