title: Thrombin generation assay as a possible tool for assessment of reduced activity of clotting factors induced by antiphospholipid antibodies and in-vitro evaluation of treatment options.
abstract: Bleeding is a rare manifestation of antiphospholipid syndrome, unless associated with reduced clotting factors or severe thrombocytopenia. Accurate assessment of the autoantibodies in plasma is very important since the autoantibodies can lead to bleeding or thrombosis. The objective of the present study was to define the inhibitors causing reduced clotting activity in a patient with antiphospholipids antibodies and to assess the potential of thrombin generation assay to assist in establishment of optimal treatment in case of major bleeding. Levels of clotting factors as well as inhibitors to factors II, V, VII, VIII, IX, X and XI were defined. For detection of inhibitors to prothrombin crossed immunoelectrophoresis was used. IgG was purified by commercial protein A column. Thrombin generation was measured using a fluorometric assay in platelet-poor and platelet-rich plasma. Inhibitors toward the activity of factors V, VII, VIII, IX, X and XI were defined and also an inhibitor to prothrombin antigen. No thrombin generation was induced in the patient's plasma by recalcification even in the presence of recombinant factor VIIa or factor VIII inhibitor bypassing activity. In contrast, addition of platelets from either donor or patient or synthetic phospholipids normalized the thrombin generation. The thrombin generation model showed that the addition of platelets and no recombinant factor VIIa or factor VIII inhibitor bypassing activity would correct thrombin generation in vitro. On this basis, platelet concentrates were administered to a patient with bleeding caused by lupus anticoagulant and low clotting factors activity.
authors.affiliation: The Amalia Biron Thrombosis and Hemostasis Research Institute, Israel.
authors.forename: Tami
authors.initials: T
authors.lastname: Livnat
authors.forename: Ariella
authors.initials: A
authors.lastname: Zivelin
authors.forename: Ilia
authors.initials: I
authors.lastname: Tamarin
authors.forename: Victor
authors.initials: V
authors.lastname: Guetta
authors.forename: Ophira
authors.initials: O
authors.lastname: Salomon
mesh_terms: D000368:Aged; D017152:Antibodies, Antiphospholipid; D016736:Antiphospholipid Syndrome / Q000473:pathology / Q000628:therapy*; D001691:Biological Therapy; D001779:Blood Coagulation Factors / Q000276:immunology*; D001780:Blood Coagulation Tests / Q000379:methods*; D006470:Hemorrhage / Q000209:etiology / Q000628:therapy*; D006801:Humans; D016682:Lupus Coagulation Inhibitor; D008297:Male; D013917:Thrombin / Q000032:analysis* / Q000096:biosynthesis
chemical_list: D017152:Antibodies, Antiphospholipid; D001779:Blood Coagulation Factors; D016682:Lupus Coagulation Inhibitor; D013917:Thrombin