Preferential binding of high molecular weight forms of von Willebrand factor to fibrillar collagen

The time- and concentration-dependent binding of von Willebrand factor to fibrillar collagen was examined by following the disappearance from plasma of ristocetin cofactor activity and factor VIII-related antigen, the functional and immunologic determinants of von Willebrand factor. Examination of both bound and unbound factor VIII-related antigen by crossed immunoelectrophoresis revealed a preferential binding of the higher molecular weight forms of von Willebrand factor to fibrillar collagen.