Activation of non-specific cytotoxic cells in Listeria-susceptible and -resistant mouse strains.

An increase in macrophage tumouricidal activity in the spleen was demonstrated following intravenous infection of genetically resistant C57BL/10 mice with Listeria monocytogenes, but not after infection of BALB/c mice. However, tumouricidal macrophages appeared in the peritoneal cavity of both strains after infection, while NK cell activity was generally higher in BALB/c mice. The activation of tumouricidal macrophages and NK cells in the C57BL/B10 mice was T independent and, at least in the peritoneal cavity, radioresistant (600 rads). The relevance of these results to the genetic control of resistance to Listeria is discussed.