Enhanced interferon-gamma production and bacterial clearance in the liver of splenectomized mice in the models of Escherichia coli injection or intestinal obstruction.

Although several studies have reported that splenectomy increases susceptibility to bacterial infections, other reports have indicated that splenectomy does not induce such susceptibility. To clarify this discrepancy, we studied the effects of splenectomy in the models of lipopolysaccharide (LPS) or Escherichia coli challenge and intestinal obstruction, focusing on cytokine production and bacterial clearance in the liver. Using C57BL/6 mice at 4 weeks after splenectomy or a sham operation, either LPS or E. coli was injected or an intestinal obstruction was made to examine the mortality, serum cytokine levels, cytokine production of the liver mononuclear cells (MNCs), and bacterial clearance in the liver. As a result, no differences were observed in survival rates after LPS or E. coli challenge between the mice with and without splenectomy. However, in a model of intestinal obstruction, splenectomized mice survived significantly longer than the sham-operated mice. Liver MNCs from splenectomized mice produced a significantly larger amount of interferon-gamma compared with those from sham-operated mice. Furthermore, bacterial counts in the liver at 2 h after E. coli injection and at 24 h after intestinal obstruction were significantly decreased in splenectomized mice compared with sham-operated mice. In conclusion, splenectomy does not impair host defense against bacteria infection provided that recovery is sufficient to allow compensatory processes in the liver to occur.