The effect of cyclosporin A on the course of murine infection by Schistosoma mansoni.

The effect of the immunomodulating substance cyclosporin A (CyA) has been evaluated in mice infected with Schistosoma mansoni. Administration of CyA at the time of infection or during the schistosomulum stage resulted in failure of the larvae to develop into adult worms. However, a serological response was noted. Administration of CyA during the establishment of the adult worm stage resulted in a reduction of the worm burden as compared to non-treated mice. The established worm pairs, however, seemed to be sterile since no eggs were demonstrated in the liver. Infection of mice with cercariae which had been exposed to CyA in vitro resulted in only a slight reduction of the worm burden for the highest concentration of CyA tested (100 micrograms/ml). The results of the study show that administration of CyA in vivo affects the host-parasite relationship in favour of the host.