Schistosomiasis in the congenitally athymic (nude) mouse. I. Thymic dependency of eosinophilia, granuloma formation, and host morbidity.

Athymic nude mice (Nu/Nu), heterozygous littermates (Nu/+), and thymus reconstituted homozygous animals (Nu/Nu TXR) were exposed to Schistosoma mansoni cercariae. A marked impairment in the development of peripheral blood eosinophilia and hepatic granuloma was observed in the Nu/Nu animal. In addition, host morbidity judged by organ weight, portal pressures and reticuloendothelial activity were less in the Nu/Nu animal. Thymus-reconstituted animals demonstrated eosinophilia, increased granuloma size, and morbidity equivalent to that shown by the Nu/+ heterozygous littermates. These studies indicate that the eosinophilia, granulomatous hypersensitivity, and ultimate host morbidity, associated with murine schistosomiasis, is dependent on thymic dependent lymphocyte function.