Suppressive effect of cyclosporin A on delayed-type hypersensitivity to syngeneic testicular cells

We have investigated the immunosuppressive effect of cyclosporin A (CsA) on delayed-type hypersensitivity (DTH) to syngeneic testicular cells (TC). DTH to syngeneic TC was induced by subcutaneous (sc) immunization with viable syngeneic TC and was augmented by a high dose of cyclophosphamide (CY)-pretreatment. DTH was suppressed by administration of CsA in a dose-dependent manner. When the mice were immunized alone or with 100 mg/kg of CY-pretreatment, 30 mg/kg or more of CsA suppressed DTH to TC. In mice immunized with 200 mg/kg of CY-pretreatment, 50 mg/kg of CsA was needed to suppress DTH. DTH is thought to play a key role in the induction and/or maintenance of experimental autoimmune orchitis (EAO). Our data show that DTH to syngeneic TC induced by immunization is suppressed by administration of CsA. Pretreatment of mice with immunization and administration of CsA suppressed DTH significantly when the mice were challenged with immunization with CY-pretreatment. However, DTH was rather enhanced significantly in mice pretreated with administration of CsA alone without preimmunization. Therefore, even though administration of CsA with immunization suppresses DTH, administration of CsA alone might rather eliminate suppressive mechanism resulting in augmentation of DTH.