The immediately vascularized skin allograft.

A model for immediate vascularization of skin was devised to examine one of the possible explanations for the differential survival rates of transplants of freely grafted skin and organs, i.e., the increased vulnerability of skin to early ischemic necrosis prior to revascularization. Female Fischer (F) rat skin was transplanted beneath the kidney capsule of tolerant female Lewis (LEW) recipients. This skin healed in and initially appeared to be normal grossly and microscopically. In 27 rats, after 30 days, the composite grafts were excised, and immediately transplanted by means of vascular anastomosis into normal LEW recipients (syngeneic to the kidney portion of the graft and allogeneic to the skin). For 5 days after transplantation of the composite graft, the skin appeared to be normal with minimal or no inflammation in a panel of 11 recipients. From the 6th to 11th day, an active rejection reaction developed at the skin-kidney interface in a panel of six rats. In 10 rats, in which the composite grafts remained in their secondary hosts for 12 to 21 days, rejection of the skin was complete. The renal portion of all composite grafts appeared to be normal histologically. All recipients of composite grafts rejected subsequent orthotopic F skin grafts in an accelerated manner, with median survival times of 8.2 +/- 0.3 days compared to 11.5 +/- 0.7 days in untreated F leads to LEW controls, demonstrating that the skin on the composite graft was fully immunogenic. These results demonstrate that immediately vascularized skin allografts between rats compatible at the major Ag-B1 locus will still be rejected within 2 weeks compared to survivals of up to 48 weeks in renal allografts in the same histocompatibility combinations, suggesting that anatomical factors are not sufficient to account for the differences in survival times between skin and solid organs.