Splenectomy does not influence outcome of pneumococcal septicemia in a porcine model

The existence of the overwhelming postsplenectomy infection syndrome in adults after traumatic splenectomy is controversial. Due to the similarity of the porcine immune system to man we chose the pig to study subsets of peripheral mononuclear cells after splenectomy and resistance to experimental Pneumococcal infection after splenic surgery and specific immunization. Female miniature pigs were assigned to four operative groups: sham operation, splenectomy, splenic resection, and heterotopic splenic autotransplantation. Hematologic and flow cytometric analysis of mononuclear cells and their subsets revealed a marked leukocytosis following splenectomy and autotransplantation but no significant shift in monocyte and B-cell numbers. Response of leukocytes to septicemia, bacterial elimination from peripheral blood, and mortality were not affected by splenectomy or spleen-preserving operations. Mortality of splenectomized animals was 18%, compared to 42% in sham-operated controls (difference not significant). Immunization protected animals from development of leukopenia, and led to an enhanced bacterial elimination, and a significantly decreased mortality of 5%, compared to 48% in nonimmune animals. Thus our data do not show significant effects of splenectomy on subsets of porcine mononuclear cells or on resistance to experimental Pneumococcal septicemia.