Pretreatment of recipients (nude rat) with donor antigens leads to prolonged survival of hamster heart xenografts.

THE INITIAL barrier to successful organ xenotrans1. plantation in discordant species is hyperacute rejection (HAR) mediated by either natural (preformed) or induced antibodies. 1•2 Hamster cardiac xenografts are normally rejected by this mechanism within 3 days when transplanted into naive LEW or athymic (nude) rats,3 which in the latter is supposedly caused by a T-cell independent process. This is contrary to the prevailing tenet that dictates that T-cell help is required for the initiation of HAR following presensitization with xenoantigens. Accordingly, we hypothesized that prior exposure of T -cell-deficient nude rats to donor antigens would not precipitate HAR of a subsequently transplanted hamster heart. This study was therefore designed to test this hypothesis.