A potential anti-coagulant role of complement factor H

Anti-phospholipid syndrome (APS) is a complex autoimmune disease, associated with recurrent venous and arterial thrombosis in various tissues. APS is associated with specific antibodies against plasma beta-2 glycoprotein 1 (beta 2-GP1), and these antibodies react with beta-GP1 bound to negatively charged phospholipids (e.g. cardiolipin) on cell membranes. Some APS patients also have autoantibodies to complement factor H (FH), a homologue of beta 2-GPI, which also binds to anionic phospholipids. beta 2-GPI has earlier been shown to inhibit the intrinsic (contact) activated blood coagulation pathway, promoted by anionic phospholipids. Here we examine whether FH could have similar anti-thrombotic properties. In vitro experiments with surface-bound phospholipids and human plasma, in the presence of RI, confirm this hitherto unreported property of FH. (c) 2014 Elsevier Ltd. All rights reserved.