Prolonged intratesticular islet allograft survival is not dependent on local steroidogenesis

The mechanisms that control the privileged survival of intratesticular organ allografts are not known. It had been postulated that the elevated levels of testicular steroid hormones, testosterone and/or progesterone, could be responsible for the inhibition of the local immune response. The goals of this study were to examine intratesticular islet allograft survival in rats in which both germ cell and Leydig cell function had been selectively destroyed. A chemical castration was induced in diabetic Sprague-Dawley rats with the chronic administration of a GnRH analog, leuprolide. In addition, both germ cell function and steroidogenesis were severely impaired by means of the surgical removal of the pituitary in diabetic rats. Pancreatic islets were isolated from Wistar-Lewis rats and were then implanted into the abdominal testes of leuprolide-treated and of hypophysectomized rats. No immunosuppression was given to the grafted rats. The results showed that long-term allograft survival occurred in the abdominal testes deprived of germ cells, of testosterone and of progesterone.