Exacerbation of Trypanosoma cruzi infection in mice treated with the immunoregulatory agent cyclosporin A.

Treatment with the immunoregulatory fungus metabolite cyclosporin A exacerbated the course of Trypanosoma cruzi infection in outbred as well as in inbred BALB/c mice. This effect was not observed in congenitally athymic, nu/nu, mice but was readily reproduced in their thymus-bearing, nu/+, littermates. These results suggest that the deleterious action of cyclosporin A on the course of experimental Chagas' disease results from activity of the drug on thymus or thymus-derived lymphocytes and emphasizes the role of T cells in host defense against T. cruzi infection.