Inactivation of factor VIII coagulant activity by two different types of human antibodies.

摘要: Human antibodies that inactivate factor VIII procoagulant activity (VIII:C) are heterogeneous in their kinetic properties. We report there here the properties of four type I and II classified according to Biggs et al. Type have second-order inactivation kinetics completely destroy VIII:C when present high concentration; more complex do not even tested undiluted. The latter correspond vivo finding some patients is detectable VIII:C, though also a significant inhibitor titer. It has been suggested antibody-antigen these retains activity. This unlikely, however, since protein-A-Sepharose (PAS) did adsorb any from mixtures with normal human plasma. An alternate possibility, reduced due steric effect factor-VIII-related protein (VIIIR, von Willebrand factor), appears be important factor, three had inactivating like they were separated instead Although fourth antibody residual coagulant was adsorbed this mixture by PAS. These data indicate anti-VIII:C react different antigenic determinants than partially blocked VIIIR.