Kinetics of type 1 and type 2 inhibitors against factor VIII.

Type 1 inhibitors develop in patients with congenital hemophilia A and are generally alloantibodies that show complete neutralization of FVIII activity. Acquired inhibitors to FVIII show type 2 kinetics, with a rapid neutralization phase, followed by an equilibrium in which residual FVIII activity can be detected in vitro.