The in vitro bactericidal activity of peritoneal and spleen cells from Listeria-resistant and -susceptible mouse strains.

Two days after Listeria-resistant (LrR) C57BL/10 mice were infected intraperitoneally with Listeria, their peritoneal macrophages demonstrated enhanced bactericidal activity beyond that seen in susceptible (LrS) BALB/c or CBA mice. Intravenous infection had no effect on peritoneal cell activity. The induction, but not expression, of the enhanced activity was radiosensitive. There was no significant difference between the strains with respect to the number of cells or cellular composition of the exudates. No difference in the in vitro chemotactic response of cells from the two strains could be demonstrated. Therefore there seems to be recruitment to the infected peritoneal cavity of C57BL/10 mice of young, efficiently bactericidal monocytes/macrophages. On the other hand, spleen cell bactericidal activity was intrinsically superior in C57BL/10 mice compared with BALB/c mice, possibly because, as a haemopoietic organ, the C57BL/10 spleen already contains high numbers of these efficient monocytes.