Von Willebrand Factor and ABO Blood Group

Abstract

Although ABO blood group antigens are widely distributed on the surface of red blood cells and epithelial cells, and in secreted body fluids, the biological function of these antigens is not clearly elucidated. Von Willebrand factor (VWF), the molecular glue between platelets and injured vessels essential for the formation of thrombotic plugs, may shed a light on their function. VWF is a unique plasma protein carrying ABO blood group antigens. Blood group influences the plasma concentration of VWF, and its level in those of blood group O is about 25% less than in non-O groups. Blood group O individuals are less sensitive to thrombotic disorders such as cardiovascular disease than non-O individuals. However, among those of blood group O, there is a significant association with high mortality in severe trauma patients. The sensitivity of VWF toward ADAMTS13, a physiological VWF-cleaving proteinase in plasma, is higher in those of blood group O, suggesting the protective role of blood group sugar chains. Although the capping sialic acid residue of plasma glycoprotein has been considered as a negatively charged barrier to hydrolyzing enzymes such as proteinase, and the penultimate galactose residue, once exposed, functions as a clearance marker for asialo-glycoprotein receptor, ABO blood group sugar chains on VWF may function as a neutral sugar chain barrier protecting the glycoprotein.