Blood group antigens on vWF from plasma and platelets. vWF was immunoprecipitated from plasma (Pls) and the platelets (Plt) extracts from normal subjects with blood groups A and B. Aliquots of each immunoprecipitates and the standard vWF (vWF, 0.5 μg) were solubilized in SDS-buffer and subjected to SDS-PAGE under reducing conditions. Proteins were transferred to a PVDF membrane followed by immunoblotting with anti-vWF antibody, anti-A and B MoAbs. vWF showed the subunit band at about 270 kD. Blood group antigens were detected on the vWF band including minor degraded band at about 140 kD prepared from plasma and the purified vWF. vWF from platelets showed no or a very faint reactivity against blood group antibody, but platelets contained smaller bands at about 110 and 130 kD that weakly reacted with anti-blood group antibodies but not with anti-vWF antibody. Numbers on the left indicate the positions of molecular mass standard (kDa). The same results were obtained when using the other two platelet specimens from blood groups A and B.