Effects of splenectomy on the retention of Salmonella enteritidis and on the hemopoietic response to Salmonella infection.

Salmonella infection induces a marked increase in the splenic granulopoiesis, but causes a reduction in hemopoiesis in the bone marrow. In this study, effects of Salmonella enteritidis infection on hemopoietic stem cells were examined in splenectomized (SX-) mice. Splenectomy emphasized hemopoietic damage in the bone marrow caused by Salmonella infection. Total nucleated cells, pluripotent stem cells (CFUs) and granulocyte-macrophage progenitor cells (GM-CFC) in the bone marrow of SX-mice all decreased markedly compared with sham-splenectomized (NX-) mice, and the recovery from the decline was also delayed. Thus, neither enhancement of the granulopoiesis nor granulopoietic recovery in the bone marrow was observed to compensate the granulopoietic response in the spleen. Splenectomy also resulted in a longlasting retention of Salmonella in the liver. The observations indicate that the spleen is the major organ to respond to bacterial invasion in regard to enhanced granulopoiesis and hence enhanced bacterial clearance.