Monoclonal antibodies against human factor VIII molecular neutralize antihemophilic factor and ristocetin cofactor activities.

Abstract
A series of monoclonal antibodies have been raised against a preparation of the factor VIII/von Willebrand factor molecule. Of the seven hybridomas showing specific activity against the factor VIII molecule in a solid-phase radioimmunoassay, three (F4.55, F4.77, and F4.264) have been shown to partially inhibit ristocetin-induced platelet aggregation and two (F4.115 and F4.415) inhibit the antihemophilic activity of the factor VIII molecule. An additional monoclonal antibody was directed against a contaminant of the factor VIII preparation and is an antifibrinogen antibody.