Effects of salmonella infection on hemopoietic stem cells in mice.

Effects of induced salmonella infection on hemopoietic stem cells were studied by comparing hemopoietic response of mice to killed and viable bacteria of an attenuated strain of Salmonella enteritidis. Results are as follows: i) A single injection with viable bacteria induced an increase in pluripotent stem cells (CFUc) and granulocyte-macrophage progenitor cells (CFUs) in the spleen and a decrease in these cells in the bone marrow, ii) A single injection or repeated injections of killed bacteria resulted in an increase of CFUs and CFUs in the bone marrow as well as in the spleen, iii) Histological examination revealed no inflammatory change that might account for the different hemopoietic responses seen with the viable and killed bacteria. Our results suggest that the hemopoietic responses in salmonella-infected mice reflect not only the influence of LPS but also effects of viable intracellular bacteria on the reticuloendothelial system constituting the hemopoietic microenvironment.