Effect of splenectomy on Gram-negative bacterial clearance in the presence and absence of sepsis

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Abstract
Severe sepsis leads to depression of the reticulo-endothelial system (RES) with delayed bloodstream clearance of particulate matter and bacteria. Splenectomy results in increased susceptibility to infection with encapsulated organisms but its effect on the resistance to postoperative Gram-negative infection has been little studied. We have investigated the effect of splenectomy on RES function by measurement of plasma fibronectin concentrations and bacterial clearance in the presence and absence of sepsis. In experiment 1, rabbits underwent splenectomy (n=8) or laparotomy only (n=8) 4 weeks before a second laparotomy. In experiment 2, animals had either splenectomy (n=8) or laparotomy only (n=8) followed 4 weeks later by devascularization of the appendix (sepsis). Plasma fibronectin concentrations and the blood clearance and organ distribution of an intravenous injection of 75Se-labelled viable Escherichia coli (2–3 × 108 colony forming units (c.f.u.)) were measured 24 h after the second operation. Splenectomy resulted in: (1) a persistent reduction in plasma fibronectin concentration in the presence and absence of sepsis, and (2) a delay in the bloodstream clearance with reduced hepatic (Kupffer cell) uptake of E. coli which was exaggerated in the septic splenectomized animal. It is concluded that the spleen may be important for Gram-negative bacterial clearance, possibly related to its influence on plasma fibronectin concentration and Kupffer cell function.