Role of the macrophage in natural resistance to salmonellosis in mice.

In vitro, macrophages from normal strain BRVR mice killed Salmonella more quickly than did macrophages from normal strain BSVS mice. Salmonella injected intraperitoneally multiplied more quickly in BSVS mice than in BRVR mice. BRVR macrophages injected intraperitoneally into BSVS mice protected against Salmonella multiplication better than did BSVS macrophages. The populations of peritoneal cells that could be washed from the peritoneal cavity of normal BRVR and BSVS mice were morphologically and numerically identical. In vitro, BSVS macrophages were as efficient as BRVR macrophages in phagocytizing virulent Salmonella. These findings all support the concept that the greater natural resistance of BRVR mice to Salmonella infection may be explained by the greater ability of normal BRVR macrophages to kill ingested Salmonella.