Adjuvant treatment with ursodeoxycholic acid prevents acute rejection in rats receiving heart allografts.

Adjuvant treatment with ursodeoxycholic acid (UDCA) for liver-transplant recipients has been reported to reduce the frequency of acute rejection episodes. To explore this effect further, UDCA was given to rats in an experimental heart transplantation model, with or without concomitant immunosuppressive treatment with antihymocyte globulin (ATG). UDCA was administered orally 7 days before and 14 days after transplantation. Rats treated with UDCA alone or in combination with ATG were compared with untreated controls and ATG-treated recipients. Adjuvant treatment with UDCA was found to induce prolonged graft survival and increase the amount of transplant tolerance in rats. Serum levels of bilirubin and aminotransferases were not altered irrespective of the UDCA dose given. The results indicate that UDCA has an immunomodulatory capacity that might not be restricted to the liver, but also might apply to other transplanted organs as well.