Intraplatelet von Willebrand factor and ABO blood group.

Levels of plasma Von Willebrand Factor (vWF) are known to be influenced by ABO Blood Group but such an influence on platelet vWF is not known. Forty-three healthy donors had blood drawn for measurement of plasma and platelet vWF, both antigenic (vWF:Ag) and functional (RCo). Twenty-six were Group O and seventeen were Group A. Groups did not differ in age, platelet count, hemoglobin, white cell counts, platelet rich plasma counts nor length of in vitro storage of samples prior to assay. Plasma levels of vWF:Ag and RCo was lower in Group O as expected. Platelet RCo was lower in Group O and such a trend was present for vWF:Ag. This influence of ABO Groups on platelet vWF was modest compared to that on plasma vWF.