Autoimmune factor VIII inhibitors.

Dramatic hemorrhage can follow the rare, spontaneous development of inhibitory autoantibodies to factor VIII (FVIII). Diagnosis, which is often delayed, relies on complex, interpretive testing for presence and titer of the inhibitor antibody. Low cross reactivity of the inhibitor to porcine FVIII supports consideration of its therapeutic use. Recombinant activated factor VII has expanded available therapeutic options beyond prothrombin complex concentrates and their activated forms. Use of genetically engineered FVIII molecules has further defined immunodominant epitopes on FVIII and may provide a therapeutic alternative. The optimal region of immunosuppressive therapy remains to be defined. Future laboratory and clinical studies are necessary for advancement of pathophysiologic knowledge and therapeutic options for patients with this uncommon but clinically important disorder.