Antihemophilic factor concentrate therapy in von Willebrand disease. Dissociation of bleeding-time factor and ristocetin-cofactor activities.

Treatment of von Willebrand disease with two plasma antihemophilic factor (AHF) concentrates, cryoprecipitate and glycine-precipitated AHF, was compared. Both concentrates were equally effective in immediately raising the plasma levels of factor VIII, the factor VIII-related antigen, and the ristocetin-related von Willebrand factor (vWF) and in stimulating a secondary rise in plasma factor VIII. Given either concentrate, the vWF activity, the antigen, and factor VIII levels were normalized in a patient with von Willebrand disease. However, correction of the prolonged bleeding time and control of bleeding occurred only with the cryoprecipitate. The bleeding-time corrective factor and the ristocetin-related vWF or platelet-aggregating factor are dissociable, distinct activites.