Assessment of the interrelationship of the biological activities detected by botrocetin and ristocetin on von Willebrand's factor from normals and patients with von Willebrand's disease

Abstract

Experiments have been undertaken to determine if the biological activities detected by ristocetin and botrocetin in plasma vWf are identical or separate. These cofactor activities have been shown to be distributed differently on vWf of different molecular size and that the multimers that interact with platelets in their plasma are also different. Although in the majority of vWd patients these cofactor activities are similar a small number of patients have been identified where this is not the case. Study of these patients has provided evidence that these biological sites on vWf are probably closely associated although distinct. It is postulated that the presence of these two distinct sites that interact with the glycoprotein Ib platelet site has a biological advantage, although the relative importance of each site separately in haemostasis is not clear and requires further study.