Modification of cutaneous leishmaniasis in the guinea-pig by cyclophosphamide.

Pretreatment of guinea-pigs with cyclophosphamide (Cy) (300 mg/kg) 3 days before cutaneous infection with Leishmania enriettii caused an increased intensity of the lesion at the site of infection and an increase in the incidence of widespread metastases. Decreased levels of circulating antibody were found from the first to fourth week after infection. Decreased delayed type hypersensitivity could only be detected beyond 4 weeks. Peritoneal macrophages obtained form guinea-pigs 3 days after Cy pretreatment showed increase rather than decreased ability to phagocytose L. enriettii. Phagocytosis of L. enriettii by peritoneal macrophages obtained from guinea-pigs pretreated with Cy 24 days previously was normal. It is suggested that more attention should be taken of antibody levels during the early phase of infection and that control of infection could be due to a synergism between antibody and cell-mediated immunity. Upset in the balance by suppression of either function might lead to the development of widespread metastatic lesions.