Protection against pneumococcal sepsis in splenectomized rats by implantation of splenic tissue into an omental pouch

Abstract

Clinical and laboratory studies have documented high susceptibility to pneumococcal infection in asplenic humans and animals. Surgeons have stressed the need to preserve the spleen when possible to maintain host resistance. It has been suggested that autotransplantation of splenic tissue might be a method of providing host resistance when total splenectomy is necessary. However, previous studies of rats have failed to demonstrate any protective effect of autotransplanted spleen. This study evaluates the effect of splenic autotransplantation into the omental pouch on pneumococcal infections in rats. Healthy, young Sprague-Dawley rats were divided into three groups of 40 each. Group I served as anesthetized sham-operated controls. Group II had a splenectomy. Group III had a splenectomy with autotransplantation of two slices of spleen 3 mm thick into surgically created omental pouches. Sixteen weeks after surgery, all animals were inoculated with Streptococcus pneumoniae type 25 in a dose of 2 X 10(7) (LD50 for splenectomized rats). Fourteen days after inoculation, all group III survivors were killed and the transplants were removed for examination. Group I had 100% survival rate following bacterial inoculation. There was a significant difference in survival rate between group II (56%) and group III (89%) (P less than 0.001). Pathologic examination of group III demonstrated hyperplastic regeneration of splenic tissue within the omental pouch. Rats bearing reimplanted splenic tissue in an omental pouch were protected against pneumococcal peritonitis.