Comparison between von Willebrand factor (VWF) and VWF antigen II in normal individuals and patients with von Willebrand disease.
Von Willebrand disease is characterised by a quantitative (type 1) or qualitative (type 2) decrease in von Willebrand factor (vWF) a multimeric glycoprotein involved in primary haemostasis. The propeptide of von Willebrand, also named vWF antigen II (vWF:AgII), is released from platelets and endothelial cells and circulates in plasma as a glycoprotein of 100 kD. In the present study, we attempted to determine whether vWF:AgII level may provide information on the synthesis of vWF, specially in patients with von Willebrand disease (vWD). To elucidate that point, we developed an ELISA and quantify the vWF:AgII in normal individuals and in various vWD patients. The propeptide molar concentration was found to be 5 nM as compared to 31 nM for mature vWF. In normal individuals, the level of vWF:AgII was significantly decreased in females from O and A blood groups. In type 2 vWD patients the level of plasma vWF:AgII appears normal in the patients with normal level of platelet vWF. In type 2 B vWD characterised by increased affinity of mature vWF for platelet glycoprotein Ib, the vWF:AgII in contrast to the vWF antigen (vWF:Ag) was not decreased. In type 2A vWD patients the level of vWF:AgII was decreased in patients with absence of high molecular weight vWF in platelets and plasma but normal in patients with increased sensitivity to proteolysis. Finally, in type 1 vWD, some studied patients have a parallel decrease in vWF:AgII and vWF:Ag whereas in others, the vWF:Ag levels were much more affected than corresponding vWF:AgII levels, as observed in some type 2 vWD patients. Thus, in contrast to that already described, the plasma vWF:AgII level cannot discriminate type 1 from type 2 vWD patients. We conclude that the vWF:AgII measurement provides additional information on the mechanisms responsible for vWD and might also contribute to the classification of vWD patients.
de Romeuf
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Laboratoire de Recherche sur l'Hémostase, Laboratoire Français du Fractionnement et des Biotechnologies, Lille, France.
Mazurier
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D000941:Antigens / Q000097:blood*; D016022:Case-Control Studies; D003470:Culture Media; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D012016:Reference Values; D014842:von Willebrand Diseases / Q000097:blood* / Q000276:immunology; D014841:von Willebrand Factor / Q000276:immunology / Q000378:metabolism*
D000941:Antigens; D003470:Culture Media; C029417:Von Willebrand antigen; D014841:von Willebrand Factor