Factor VIII antigen in the vessel walls in von Willebrand's disease and haemophilia A

Biopsy specimens of superficial veins were obtained from 5 patients with von Willebrand's disease and 3 patients with hemophilia A and studied for factor VIII antigen with the aid of a direct immunofluorescent technique. Fifteen healthy men served as controls. In all the controls, a bright specific fluorescence was observed in the intimal layer of the vein, but 3 patients with severe von Willebrand's disease lacked the antigenic protein in the intima. The fluorescence was, however, present in one patient with moderately severe von Willebrand's disease and in one patient with an atypical form of the disease, as well as in 3 with classical hemophilia. When protein was found in the vessel wall, it was always demonstrable in the plasma, and vice versa. It is assumed that the von Willebrand factor - factor VIII protein exerts an effect on primary hemostasis also locally in the vessel wall.