IMMUNE RESPONSE TO CANINE LYOPHILIZED VEIN ALLOGRAFTS

Abstract

423 We investigated the immune response to lyophilized allograft vein transplants implanted in the canine venous system without immunosuppression. Lyophilized veins (n=20) were prepared by vacuum freeze drying canine jugular veins within 24 hours of harvest. The grafts were stored at room temperature for two weeks before they were transplanted as interposition grafts into the femoral veins of 10 mongrel dogs. Each animal received an end to end interposition autograft (n=10) vein in one limb, and a randomly assigned allograft (n=10) in the opposite limb. Typing for three blood group factors (DEA-1.1/1.2/7) was obtained. Pre and posttransplant lymphocyte crossmatches were performed on each animal. Transplants were performed independent of blood type or crossmatch result. Aspirin was given perioperatively. Vein grafts were harvested after six weeks, and histologic evaluation was performed. Both allografts and autografts had a patency rate of 70%. Positive crossmatch was not associated with graft occlusion. None of the six negative preoperative crossmatches became positive postransplant. Lymphocytic CD3 + T cell infiltrate as measured by cell count per high power field, was not significantly different between allografts and autografts (1.44±0.82 vs. 1.08±0.42, p=N.S.). Cellular infiltrate was similar in allografts regardless of positive (n=4) or negative (n=6) crossmatch results (1.46±0.95 vs. 1.43±0.821). There was a trend for more cellular infiltrate in allografts implanted in blood type mismatched (n=3) recipients (1.97±1.17 vs. 1.22±0.61 p=N.S.). Lyophilized vein allografts implanted in the venous system without immunosuppression have the same patency rate as autografts. CD3 + T lymphocytic infiltrate and patency rates are similar regardless of positive pretransplant crossmatch or blood type mismatch. Lyophilized vein allografts represent an alternative for venous reconstruction. Supported in part by a grant from the Physicians Medical Education and Research Fund, Knoxville, TN.