Determination of hindlimb transplantation-induced vascular albumin leakageand leukocyte activation during the acute phase of rejection

Following transplantation, the microvascular endothelium and endothelial ce lls play a critical role in allograft rejection, as well as response to sur gical trauma. In this study, endothelial-cell damage was assessed through m icrovascular permeability, and the role of surgical trauma was evaluated du ring the acute phase of limb allograft rejection. Eighteen isograft and 18 allograft composite-tissue transplantations were performed between 72 rats. At 24-hr, 72-hr, and 7-days follow-up, microvascular permeability, leukocy te activation, functional capillary perfusion, red-blood-cell velocity, ves sel diameter, and an endothelial edema index were measured. The permeabilit y index (Pl) was statistically significantly greater in the allografts at a ll follow-up points, compared with the isograft controls (p <0.001). The nu mber of rolling leukocytes was significantly greater in the allografts at 2 4 and 72 hr; the number of sticking and transmigrating leukocytes was great er at all three follow-up points; and the number of rolling lymphocytes was greater at 7 days (p <0.05). These findings demonstrate the increased reje ction phenomenon in allografts, and the increased susceptibility to ischemi a and reperfusion injury, compared with isograft transplants. Increased leu kocyte activation and acute destruction of endothelial-cell barrier functio n were demonstrated during the acute rejection period following composite l imb allotransplantation.