Immunological Studies of Factor VIII (Antihaemophiliac Globulin) in Haemophilia A

Abstract

PATIENTS with haemophilia A have recently been divided into two groups; one characterized by a functionally defective factor VIII (AHG) molecule in the plasma, which is immunologically similar to normal factor VIII but lacks procoagulant activity^1–3, while the other seems to represent a true deficiency of factor VIII, for both procoagulant and immunological properties of factor VIII are absent. These conclusions are based on the ability of normal and some haemophiliac plasma to neutralize human antibodies from patients with spontaneously occurring inhibitors against factor VIII or from multi-transfuscd haemophiliacs who have developed circulating inhibitors directed against factor VIII. These studies have divided haemophilia A into those with cross reactive material (CRM +) and those without (CRM −). Other methods of characterizing this genetic polymorphism in haemophilia have not been reported. We have used immunoelectrophoresis and antibody neutralization with a heterologous antibody to show a similar division of haemophilia A into a small group of CRM+ (15%) and a larger group of CRM− (85%). Immunoelectrophoresis and antibody neutralization studies have also been described in factor X polymorphism⁴.