Regulation of spleen growth and portal pressure in hepatic shcistosomiasis.

Growth rate and histology of splenic autotransplants in subcutaneous pockets were compared with those of autotransplants in the extrahepatic portal bed in splenectomized mice infected with cercariae of Schistosoma mansoni and in splenectomized uninfected controls. By the fifteenth week after transplantation (and tenth week after injection of cercariae) subcutaneous transplants gained 6.5 times and omental transplants 8.2 times more weight in infected animals than corresponding transplants in uninfected animals. Portal pressures averaged 11 to 13 cm of water in infected animals with transplants and 17 cm in those with intact spleens (compared to that of 6 to 7 cm in controls). Hyperplasia of white pulp with increase in germinal center activity characterized transplants as well as intact spleens of infected animals. The results suggest that a) During the first 10 weeks of experimentally induced infection, portal congestion is not the predominant mechanism regulating increased spleen growth; and b) An intact enlarged spleen appears to contribute to elevated portal pressure.