Features of the patient’s vWF. (A) FVIII binding ability of plasma vWF. Serial dilutions of plasma samples were incubated into a microtiter plate coated with anti-vWF polyclonal antibodies. A constant amount of recombinant FVIII (0.1 U/mL) was then added and the activity of FVIII bound to immobilized vWF was determined using a chromogenic assay. The amounts of vWF captured by immobilized antibodies were measured by ELISA using a peroxidase-conjugated MoAb as described.25 Plasma samples : (•), pool of normal plasmas; (▪), patient’s plasma. Each dilution sample was analyzed in duplicate and the results were averaged. (B) Multimeric pattern of normal and patient’s vWF. Plasma and platelet lysate samples were electrophoresed in SDS-1.5% agarose gel and vWF was visualized with alkaline-phosphatase conjugated anti-vWF polyclonal antibodies. Lane 1, pool of normal plasmas; lane 2, patient’s plasma; lane 3, patient’s platelet lysate; and lane 4, normal platelet lysate.