Vascularized bone marrow transplantation in rats: evidence for amplification of hematolymphoid chimerism and freedom from graft-versus-host reaction.

T HE PERSISTENCE of donor-derived leukocytes. which are capable of proliferating. trafficking, and interacting within the recipient tissues. has been proposed as a biological mechanism which facilitates the induction of acquired tolerance after whole organ transplantation. l Although the details of the intrinsic mechanisms which underlie the bidirectional immune modulation are unknown. it is speculated that augmentation of chimerism will favor graft acceptance and may eventually lead to a drug-free existence. Rat hind limb contains mature Iymphocvtes (regional lymph nodes). nonparenchymal tissue (skin and muscle), and vascularized bone marrow. which after transplantation provides a continuous supply of donor-derived progenitor cells. [n the present study. we compared the level of chimerism induced experimentally by either vascularized hone marrow transplantation (VBMTx) using the rat hind limb allograft model. or else bv infusion of t:ither lymph node or bone marrow cells. Their intiuence on the incidence and severitv of graft-versus-host disease (GVHD) was also assessed.