[Prolonging transplant survival time by PUVA treatment of the transplant recipient. Significance of cis-urocanic acid].

A PUVA treatment of the recipients of murine tail skin grafts led to a significant prolongation of transplant survival. A possible mechanism of the systemic immunomodulatory effects of ultraviolet light in the organism is the transformation of urocanic acid in the skin from its trans- to the cis-isomer, which acts as a mediator on the immune system. A treatment of graft recipients with cis-, but not trans-urocanic acid also prolonged graft survival. The rejection of secondary grafts and the humoral immune response of mice to sheep erythrocytes were not influenced by cis-urocanic acid. These results implicate that cis-urocanic acid may be get use in clinical organ transplantation and dermatology.