The effect of blood transfusions on rat corneal graft survival.

To determine whether a preoperative blood transfusion could influence corneal graft rejection, full-thickness 3 mm orthotopic corneal grafts were performed in Dark Agouti (DA) rats from syngeneic (DA) or allogeneic (Brown Norway and Lewis) inbred donors and in Lewis rats from syngeneic (Lewis) or allogeneic (DA) donors. Rats with syngeneic grafts showed no signs of rejection. The corneal buttons remained clear indefinitely, although vessels grew up to the wound. All allogeneic grafts in nontransfused rats rejected between 6 and 25 d (the interval depended on the strain combination). The median survival of BN to DA grafts was 9 d, and the median survival of Lewis to DA grafts was 7 d. Therefore, both can be described as high responder strain combinations. The DA to Lewis grafts survived longer, with a median survival of 15 d. This was described as a low responder strain combination. A single preoperative transfusion of blood from the same strain as the corneal graft donor prolonged the survival of corneal allografts in the two high responder combinations, an effect called active enhancement. However, a blood transfusion did not enhance the survival of allografts in the Lewis rat. Corneal grafts from animals of a third party strain were not enhanced but were rejected, following the same time course as nontransfused controls. Thus, preoperative donor-specific blood transfusion specifically delayed the immune response to corneal allografts in some strain combinations but not in others. This may limit the clinical application of this technique.