Abstract
Von Willebrand factor (VWF) is a 500- to 15 000-kDa multimeric protein circulating in the blood. When VWF has a higher molecular weight, its hemostatic activity is greater. The size distribution of VWF multimers is usually analyzed by SDS-agarose gel electrophoresis followed by immunoblotting. We found that the most commonly used anti-VWF antibody cross-reacted with fibronectin in VWF multimer analysis. In addition, since the apparent molecular weights of VWF and fibronectin are almost identical, these molecules were difficult to distinguish by SDS-polyacrylamide gel electrophoresis followed by immunoblotting. Cross-reactivity between the anti-VWF antibody and fibronectin was inhibited by pretreating the antibody with fibronectin-coated plates. To obtain accurate data using anti-VWF antibodies, it is necessary to be aware of the possibility of cross-reactivity with fibronectin.