Neutrophils prevent extracellular colonization of the liver microvasculature by Salmonella typhimurium

The early course of hepatic infection with the facultative intracellular bacterial pathogen Salmonella typhimurium was examined in control mice and in mice selectively depleted of neutrophils by treatment with a granulocyte-specific monoclonal antibody. The results show that >200-fold more salmonellae were recovered in livers of the latter group of mice than in livers of the former group by 24 h of parenterally initiated infection. Comparative histological examination of the livers from both groups of mice indicated that neutrophils participate in early anti-Salmonella defense in the liver in part by aborting infection in permissive hepatocytes and by inhibiting extracellular bacterial colonization of the hepatic microvasculature. It is shown in addition that systemic salmonellosis was also severely exacerbated in neutropenic mice infected intragastrically with the pathogen.