A comparison of five different rabbit antisera to factor VIII and the demonstration of a factor VIII related antigen in normal and von Willebrand's disease platelets.

Abstract

<h2>Abstract</h2> Five different antisera raised against "factor VIII" have been compared with respect to their activity in inhibiting procoagulant factor VIII, in immunofluorescent studies and by immunoelectrophoretic techniques. A method for titrating precipitating antibody to factor-VIII related protein using counter-immuno-electrophoresis is described. Four of the antisera possessed both precipitating antibody to factor VIII related protein and inhibitory activity against procoagulant factor VIII. These antisera reacted by immunofluorescence or immunoprecipitation methods with a factor VIII related antigen or antigens in normal platelets and in the platelets of a patient with severe von Willebrand's disease although antigen could not be detected in the patient's plasma. The other antiserum had specific precipitating activity against factor VIII related protein but it did not inhibit procoagulant factor VIII. It reacted with normal platelets by both immunoprecipitation and immunofluorescent techniques but it did not react with the severe von Willebrand's disease platelets. The results show that although the antisera appeared to contain a single antibody giving reactions of identity when examined by simple immunodiffusion some of them in fact contained antibodies with different characteristics.