Factor VIII Binding Ability of von Willebrand Factor in Several Fractions of Normal Plasma and Plasma from Several Types of von Willebrand Disease

Binding ability of plasma von Willebrand factor (vWF) to purified factor VIII (F. VIII) in normal subjects and patients with von Willebrand disease (vWD Type IIA, IIB, IIC) was analysed in a solid phase assay. A vWF fraction, mainly containing large multimer-vWF, was obtained from gel filtration of cryoprecipitate, whereas another vWF fraction, containing small multimer-vWF, as cryo-supernatant. Binding ability of vWF in small and large multimer-vWF fractions was identical. Binding ability of vWF in the plasmas from vWD Type IIA, IIB and IIC was found to be within normal range. These results suggested that the vWF binding to F. VIII was independent from multimeric structure.