title: Quantification of lupus anticoagulants in clinical samples using anti-beta2GP1 and anti-prothrombin monoclonal antibodies.
abstract: Quantification of lupus anticoagulant (LA) in clinical samples is hampered by the lack of a suitable standard of activity. We evaluated the use of mAbs displaying LA activity for this purpose. As most patient samples contain both beta2Glycoprotein I (beta2GP1) and prothrombin dependent LA, a combination of two mAbs, one of each specificity, was added to normal plasma in a concentration from 0 to 60 microg/ml. Eight assay systems using different reagents and instruments were used. The calibration curves were linear for all but one, with marked differences between the responsiveness to each mAb. A panel of plasmas from 69 patients with persistent LA diagnosed using the SSC-ISTH criteria was tested. An antiphospholipid syndrome (APS) was present in 40, whereas 29 were asymptomatic. LA activities of individual plasmas varied between assays (p < 10(-4)), but homogeneous subgroups were identified. In a majority of samples, LA activity displayed a prothrombin-dependent profile, with a variable contribution of beta2GP1-dependent activity. The latter was associated to beta2GP1 antibodies detected by solid-phase immunoassay. By using 3 dilute Russell viper venom time assays, higher LA titers were found in APS, compared to asymptomatic patients (p <0.05).
authors.affiliation: Hopital Côte de Nacre, Caen, France.
authors.forename: A
authors.initials: A
authors.lastname: Le Querrec
authors.forename: J
authors.initials: J
authors.lastname: Arnout
authors.forename: D
authors.initials: D
authors.lastname: Arnoux
authors.forename: J Y
authors.initials: JY
authors.lastname: Borg
authors.forename: C
authors.initials: C
authors.lastname: Caron
authors.forename: L
authors.initials: L
authors.lastname: Darnige
authors.forename: B
authors.initials: B
authors.lastname: Delahousse
authors.forename: G
authors.initials: G
authors.lastname: Reber
authors.forename: P
authors.initials: P
authors.lastname: Sié
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal; D016736:Antiphospholipid Syndrome / Q000175:diagnosis / Q000209:etiology / Q000276:immunology; D001323:Autoantibodies / Q000097:blood / Q000145:classification; D001780:Blood Coagulation Tests; D002138:Calibration; D005260:Female; D006023:Glycoproteins / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D007118:Immunoassay / Q000592:standards; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D016682:Lupus Coagulation Inhibitor / Q000097:blood* / Q000145:classification / Q000276:immunology; D008297:Male; D011516:Prothrombin / Q000276:immunology*; D012680:Sensitivity and Specificity; D053482:beta 2-Glycoprotein I
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D006023:Glycoproteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I; D011516:Prothrombin