BINDING TO PHOSPHOLIPID PROTECTS FACTOR-VIII FROM INACTIVATION BY HUMAN-ANTIBODIES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 101  (1) , 34-43
Abstract
The addition of purified factor IXa and phospholipid to factor VIII concentrate protected the VIII:C [factor VIII clotting activity] from inactivation by human antibodies. This protective effect was due largely to the phospholipid. Addition of phospholipid alone gave substantial protection against even high-titer antibodies, as shown by measurements of thrombin generation and VIII:C assays. Increasing concentrations of phospholipid led to significant reductions in the amount of VIII C:Ag [factor VIII clotting antigen] detected by an IRMA [immunoradiometric assay] method, up to 70% of the original VIII C:Ag being lost at the highest concentration of phospholipid. Phospholipid binding plays an important part in the procoagulant activity of factor VIII and human antibodies to VIII:C are directed largely at the phospholipid binding site. The addition of phospholipid to factor VIII concentrates could have important clinical applications in the treatment of hemophiliacs with antibodies to factor VIII.