The effect of immunosuppressants on experimental infection with Fasciola hepatica.

Results are presented on the effect of immunosuppressive substances such as chlorambucil, cyclophosphamide, azathioprine, amethopterine and a cortizone derivate of betamethasone, on the development of Fasciola hepatica in the rat. The suppression of the immune response of the host to immunosuppressants was reflected in an earlier start of migration of the flukes to the common bile duct, and in an earlier onset of egg production as compared with that in the controls. Of the substances employed, cyclophosphamide and betamethasone were the most effective ones within the period from week 2--6 p.i., which is the time during which the migration of the flukes in the liver parenchyma is highest. Pathological changes in the liver of the animals were less marked than those of the infected controls. Evidence was obtained on an increased pathogenicity of infective larval flukes causing a higher mortality of the hosts in comparison with that of the control animals. On the other hand, the administration of immunosuppressants did neither influence the total number of developed flukes nor the appearance of eosinophilia in the peripheral blood of the treated animals.