Homograft crossmatching is unnecessary due to the absence of blood group antigens

Background. Homograft valves are subject to calcification and structural de generation in the long term. Blood group matching is performed in many cent ers, and it remains controversial whether immunologic responses associated with potential blood group incompatibility contribute to the degeneration o f unmatched homografts. We studied the expression of carbohydrate blood gro up antigens on valve endothelium of thawed aortic homograft valves and fres hly harvested human cardiac valves. Methods. Cryopreserved human aortic homograft valves and freshly harvested human aortic, pulmonary, mitral, and tricuspid valves were incubated with a ntibodies to A, B, and O blood group antigens. Results. Cardiac microvascular endothelium stained positively with antiendo thelial CD31 antibody in both cryopreserved and fresh tissue. Cryopreserved valve endothelial lining rarely stained positively for CD31, in contrast t o fresh valves, which always stained positive. Cryopreserved or fresh cardi ac microvascular endothelium strongly expressed A, B, or H antigens. In con trast, ABH antigens were not detectable on homograft or fresh cardiac valve endothelium. Conclusions. The absence of expression of carbohydrate antigen on valvular endothelium suggests that blood group incompatibility does not play a signi ficant role in homograft degeneration. (C) 2001 by The Society of Thoracic Surgeons.