FACTOR VIII COAGULANT ACTIVITY AND FACTOR VIII-LIKE ANTIGEN: INDEPENDENT MOLECULAR ENTITIES

Abstract

Factor VIII coagulant activity (VIII_C) and the von Willebrand's disease antigen (Factor VIII-like antigen, vW-Ag) are biologically linked, and it has been suggested that they reside on the same molecule. However, insolubilized human isoantibody to VIII_C and rabbit antiserum containing antibodies to VIII_C and vW-Ag differentially bind and remove these entities from plasma, thus physically segregating one from the other. These findings indicate that Factor VIII coagulant activity resides on a molecule distinct from that expressing the von Willebrand's antigen.