Gonadotropins moderate rejection of trophic-specific congenic testes grafts.

Factors that favor graft survival of fetal and neonatal testis relative to adult testis were explored by studying the effects of rapid growth on immunogenicity. Tissue-specific growth was initiated by elevated gonadotropins created by oophorectomy and allografted target testes were examined. Three-day postnatal testes were implanted under the subrenal capsule of oophorectomized (as confirmed by elevated gonadotropins) and nonoophorectomized females. Immunosuppressive therapy with cyclosporine A was administered to selected animals of both groups. Preliminary studies in outbred rats and more extensive studies in allogenic/congenic mice (C57BL/6J to B10.A) showed that testicular allografts exposed to the elevated gonadotropins caused by previous host oophorectomy grow larger, have less lymphocytic infiltrate, and show better preservation of architecture than do allografts in nonoophorectomized female recipients. The graft survival resulting in vivo from elevated gonadotropins approximated that permitted by either maximal immunosuppression or syngeneic transplantation.