title: The contribution of anti-prothrombin-antibodies to lupus anticoagulant activity--discrimination between functional and non-functional anti-prothrombin-antibodies.
abstract: The presence of lupus anticoagulant (LAC) is strongly correlated with a history of thrombosis in patients with SLE. LAC activity can be caused by anti-prothrombin (FII)- and/or anti-beta2glycoprotein I (beta2GPI)-antibodies. In the present study, the contribution of anti-FII-antibodies to LAC activity was measured in 28 LAC positive plasmas. Plasmas were incubated with prothrombin or BSA, immobilized on CNBr-activated Sepharose, to absorb all anti-FII-antibodies. In 4 out of the 28 plasmas LAC activity was completely dependent on anti-FII-antibodies. In 7 out of the 28 plasmas, anti-FII-antibodies did not contribute to LAC activity. These anti-FII-antibodies can be regarded as non-functional antibodies. In the majority (17/28) of the samples, LAC activity within a single plasma was caused by a combination of antibodies with different specificities. Both dRVVT and KCT showed comparable sensitivity for the detection of functional anti-FII-antibodies. In conclusion, in most samples LAC activity is not caused by anti-FII-antibodies alone but by a combination of different types of antibodies. The presence of LAC activity and anti-FII-antibodies in one plasma does not automatically implicate that these antibodies are responsible for the LAC activity.
authors.affiliation: Department of Haematology, University Hospital Utrecht, The Netherlands.
authors.forename: D A
authors.initials: DA
authors.lastname: Horbach
authors.forename: E
authors.initials: E
authors.lastname: van Oort
authors.forename: R H
authors.initials: RH
authors.lastname: Derksen
authors.forename: P G
authors.initials: PG
authors.lastname: de Groot
mesh_terms: D000918:Antibody Specificity; D016736:Antiphospholipid Syndrome / Q000150:complications / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D001327:Autoimmune Diseases / Q000150:complications / Q000276:immunology; D006801:Humans; D008137:Longitudinal Studies; D016682:Lupus Coagulation Inhibitor / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000276:immunology; D010314:Partial Thromboplastin Time; D011516:Prothrombin / Q000276:immunology*; D011517:Prothrombin Time; D012680:Sensitivity and Specificity; D019851:Thrombophilia / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D016682:Lupus Coagulation Inhibitor; D011516:Prothrombin