Immunoaffinity purification of factor VIII

The development of factor VIII concentrates has greatly facilitated hemophilia care and has made the home care of hemophilia possible. However, factor VIII concentrate that has been produced using traditional methods contains large amounts of foreign proteins and viruses. This has resulted in the development of immunologic abnormalities in many hemophiliacs and has exposed many of these patients to blood-borne viruses such as the human immunodeficiency virus (HIV) and hepatitis viruses. Factor VIII circulates in plasma in complex with the von Willebrand factor (vWF). Both factor VIII and vWF have been purified and monoclonal antibodies (mAb) have been generated to both of these proteins. When bound to a solid support, these mAb's can be used to isolate selectively the proteins of interest. Recently, two separate procedures have been used in the immunoaffinity purification of factor VIII on a commercial scale. One product (Monoclate) has been prepared using a mAb to the vWF bound to a chromatography column. The other product (Hemophil M) uses immobilized mAb to the factor VIII molecule. Factor VIII concentrate purified using either of these approaches is far more pure than traditional factor VIII concentrates. In addition, the use of both viral purification and viral inactivation procedures has greatly reduced the risk of viral contamination. Early clinical studies have demonstrated that these products are effective in treating bleeding episodes and that the risk of viral infection with HIV or hepatitis viruses is low. Factor VIII concentrate produced using mAb technology appears to be the product of choice in previously untransfused hemophiliacs. Its role in the treatment of patients who have already been infected with HIV is less clear.