Experimental studies on allogeneic transplantation have shown that recipient dendritic cells (DC) play a role in peripheral tolerance as well as in rejection of allografts. It is not known whether DC exert their tolerogenic function in the graft or in recipient lymphoid tissue. To answer this question we created a chimeric heart model deprived of its own DC and repopulated by recipient DC. The rationale for this model was to observe whether recipient mature and immature DC located in the graft attenuate recruitment and stimulation of recipient lymphocytes, subsequently prolonging graft survival. Vascularized bone marrow transplants (VBMTx) from the prospective recipient to the lethally irradiated heart donor, which function for a period of 14 days, were used to replace donor DC with prospective recipient either mature or immature DC. Replacement of the donor heart with either of these cellsdid not prolong graft survival. The intra-graft microchimerism did not mitigate the allogeneic rejection reaction.

Keywords: Heart, Transplantation, Rejection, microchimerism