CD4+ T Cells Specific for Factor VIII as a Target for Specific Suppression of Inhibitor Production

Abstract
Some hemophilia A patients, when treated with factor VIII (fVIII) products to control bleeding episodes, develop antibodies (Ab) to surface domains of fVIII that are essential for its procoagulant function 1,3 Development of fVIII inhibitors is a serious therapeutic complication that affects 20 – 25% of patients with hemophilia A 1,3 Individuals without congenital fVIII deficiency may also develop pathogenic autoimmune inhibitory Ab to fVIII that cause acquired hemophilia, a rare yet severe bleeding disorder (4,5 ). FVIII inhibitors are high affinity IgG, and their synthesis requires the intervention of fVIII specific CD4+ T helper cells.