A study of Schistosoma mansoni reinfection in thymectomized rats

Thymectomized irradiated rats were reconstituted with bone marrow from thymectomized donors subjected to chronic thoracic duct drainage. These animals (“B rats”) showed a profound suppression of T-cell activity in various in vitro and in vivo tests. B rats of the Fisher strain infected twice with S. mansoni did not exhibit any resistance to reinfection, while intact controls showed a significant reduction in the number of challenge worms. High levels of peripheral eosinophils were present in infected intact rats, while B rats showed only modest eosinophilia under the same conditions of infection. Granuloma formation and other cellular inflammatory reactions in the liver of infected animals were almost completely abolished in B rats.