To investigate the synergistic effect of low dose of CsA and 1, 25-dihydroxyvitamin D₃ in the treatment of acute rejection following orthotopic liver transplantation.

Orthotopic rat liver transplantation model performed according to Kamada's technique was employed. SD and Wistar rats served as donors and recipients respectively. Recipients were divided randomly into 4 groups. Group Ⅰ: Control; Groups Ⅱ and Ⅲ were treated with full dose of CsA and 1, 25-dihydroxyvitamin D₃ respectively; Group Ⅳ was subjected to administration of low dose of CsA combinated with 1, 25-dihydroxyvitamin D₃. Survival posttransplantation as well as pathological rejection grade and IFN-γmRNA expression on the day 5, 7, 12 after transplantation was observed.

In group Ⅳ, the survival in 5/6 recipients were significantly increased in comparison with Group Ⅰ (P<0.05), but not significantly different from that in group Ⅱ or group Ⅲ (P>0.05). The average pathologic rejection grade in group Ⅳ was 0.67, 1 and 0.67 at the 5 th, 7 th, 12 th day posttransplantation respectively, markedly lower than in group Ⅰ (P<0.05). IFN-γ mRNA expression in the liver tissues in group Ⅳ was at a low level on each time point. IFN-γ mRNA expression was not significantly different (P>0.05) from either group Ⅱ or group Ⅲ except on the day 7 posttransplantation.

Administration of low dose of CsA combined with 1, 25-dihydroxyvitamin D₃ is synergistic in preventing allografts from acute rejection and prolonging survival of recipients after orthotopic liver transplantation.

Cyclosporine A; Vitamin D; Liver transplatation; Graft rejection; Immunosuppressant