Hemophilia A, which affects 1-2:10,000 live-born male neonates, is a genetic coagulopathy with recessive inheritance linked to the X chromosome. These individuals have low concentrations or no coagulation factor VIII (FVIII) in the plasma and suffer from mild, moderate and severe bleeding depending on the circulating FVIII activity. These patients need frequent protein infusions and approximately 30% of them develop alloantibodies against the exogenous protein. Anti-FVIII antibody synthesis initiates when the exogenous FVIII is internalized by antigen presenter cells, degraded and presented to CD4+ T-cells as peptides associated to the class II major histocompatibility complex (MHC). Some risk factors (patient/treatment) may be related to the development of this immune response. Thus, FVIII gene mutations and polymorphisms of genes involved in immune response are molecular candidates of immunogenic determinants in the predisposition for inhibitor development. As it is not fully understood and controlled, the development of immune response against FVIII constitutes a major problem in the treatment of hemophilia A which aims at minimizing the deleterious consequences. Some therapeutic alternatives have been effective (anti-CD20, plasmapheresis, prothrombin complex concentrates, activated prothrombin complex concentrates, human activated factor VII), but removal or neutralization of specific anti-FVIII inhibitors has not been achieved yet.
Hemophilia A; inhibitors; factor VIII; immunology