Abstract
Cryoprecipitate has proved to correct the hemostatic defects in von Willebrand's disease (vWD). However, recent studies have revealed that transmission of the AIDS retrovirus (HIV) occurs through exposure to blood products including cryoprecipitate. Treatment with heat-treated factor VIII concentrates may have certain advantages over treatment with non-heated products, if these preparations are efficacious in vWD and related disorders. We investigated the multimeric composition of von Willebrand factor (vWf), contents of vWf antigen (vWf: Ag) and ristocetin cofactor (RCof) in the heat-treated concentrates and cryoprecipitate, and their capacity to directly induce aggregation of platelet-type vWD platelets in vitro. The vWf multimers were visualized by a newly developed, immuno-enzymatic staining of the gel, following a discontinuous SDS-agarose gel electrophoresis. The RCof/vWf: Ag ratio was around 1.0 in cryoprecipitate, and ranged from 0.19 to 0.96 in factor VIII concentrates. Among four commercially available concentrates studied, Haemate P contained the most high-molecular-weight multimers of vWf and the highest RCof relative to vWf: Ag, and induced the aggregation at the lowest concentration. When infused into a patient with platelet-type vWD, Haemate P (14.4 U vWf: Ag/kg) shortened the prolonged bleeding time and caused spontaneous platelet aggregation in vitro with a mild diminution of platelet count. These results indicate that some of the heat-treated factor VIII concentrates may provide a safer, yet still effective, treatment for platelet-type vWD, and possibly for various types of vWD.
