ABSTRACT
Vascularized bone allografts (VBAs) could be useful adjuncts to the clinical reconstructive
surgeon's arsenal. These grafts are known experimentally to be subject to host rejection.
One way to control the rejection problem would be to develop specific immune unresponsiveness
via host conditioning. Using a proven reliable model in inbred rats for studying heterotopic
VBA transplantation, recipient animals were conditioned preoperatively with third-party
unrelated blood, donor-specific blood (DSB) alone and with cyclosporine, and ultraviolet
irradiated donor-specific blood. The combination of DSB plus cyclosporine delayed
rejection of grafts across a strong histocompatibility barrier for three to four weeks.
However, rejection was delayed across a weak histocompatibility barrier for five to
six weeks using this same host pretreatment. The implications are that specific immunosuppression,
although possible, is difficult to achieve in VBA transplantation, and that such techniques
will rely on tissue-matching to minimize the genetic disparity between graft and host.
