In vitro alteration of canine renal allografts with cyclophosphamide metabolites

4-Hydroxycyclophosphamide (4-HCY) is generated spontaneously in cryoprecipitated plasma from synthesized 4-hydroperoxycyclophosphamide (4-HPCY); its immunosuppressive and cytotoxic effects seem to depend on milieu, temperature, time, and dosage. Our preliminary results suggest that prolonged canine renal allograft survival can be achieved with grafts exposed to CY metabolites (4-HPCY and PM) in vitro for 24 hr. Further studies with larger dosages (greater than or equal to 100 micrograms/ml of 4-HPCY) are indicated to test these suggestions conclusively.