Synergistic effect of donor pretreatment with 8-methoxypsoralen and ultraviolet irradiation of the graft plus azathioprine and prednisolone therapy in prolonging rat renal allograft survival.

Pretreatment of the kidney donor with 8-methoxy-psoralen (8-MOP) and direct longwave ultraviolet (UVA) irradiation of the kidney graft (PUVA therapy) significantly prolonged survival in allogeneic recipients. 40% of the recipients survived more than 100 days with normal transplant function. The addition of standard clinical immunosuppressive agents azathioprine and prednisolone (both at dosages of 15 mg/kg body weight/day for 21 days) to the PUVA therapy further improved graft survival rate, with a recipient survival rate of 62.5%. The two drugs alone were less effective in prolonging graft survival rate (28.5%). A synergistic effect of PUVA therapy and standard immunosuppressive treatment with azathioprine and prednisolone was demonstrated. This suggested a possible clinical application of this type of immunosuppression and immunoregulation.