title: Specificities of platelet autoantibodies and platelet activation in lupus anticoagulant patients: a relation to their history of thromboembolic disease.
abstract: Lupus anticoagulants (LA) prolong in vitro phospholipid-dependent coagulation tests, but are associated with thromboembolic disease (TE). However, a subgroup of individuals with LA has no TE, and it is therefore desirable to distinguish those at risk for TE from those without. Whether platelets have a primary role in the development of TE is not clear yet. We determined platelet autoantibodies to identify a specific platelet target which is associated with platelet activation in 97 patients with a long history of detectable LA, 65 patients with TE (LA/TE+), and 32 individuals without TE (LA/TE-). Thrombocytopenia was more common in the LA/TE- than in the LA/TE+ group (P < 0.05). Both groups had platelet antibodies, but the frequency of antibodies was lower in LA/TE+ than LA/TE- patients (P < 0.01), who had higher antibody titres against glycoprotein IIb/IIIa and glycoprotein Ib/IX (P < 0.05). Also, their platelets were more activated, as determined by PAC-1 binding (P < 0.01). These differences were also noted if patients with arterial thrombosis were evaluated separately. These findings in LA/TE- individuals were similar to those in patients with chronic autoimmune thrombocytopenia. However, there was no autoantibody target identifiable to distinguish between LA/TE- from LA-TE+ individuals. We therefore conclude that the presence of platelet antibodies, even if associated with platelet activation, is not sufficient to dispose LA patients to thromboembolic disease.
authors.affiliation: Clinic for Blood Group Serology, Medical University of Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Schallmoser
authors.forename: C
authors.initials: C
authors.lastname: Rosin
authors.forename: R
authors.initials: R
authors.lastname: Vormittag
authors.forename: M
authors.initials: M
authors.lastname: Brunner
authors.forename: D
authors.initials: D
authors.lastname: Dunkler
authors.forename: I
authors.initials: I
authors.lastname: Pabinger
authors.forename: S
authors.initials: S
authors.lastname: Panzer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016736:Antiphospholipid Syndrome / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000276:immunology*; D002648:Child; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000276:immunology*; D008875:Middle Aged; D015539:Platelet Activation; D010980:Platelet Membrane Glycoproteins / Q000276:immunology; D011897:Random Allocation; D013921:Thrombocytopenia / Q000276:immunology; D013923:Thromboembolism / Q000276:immunology*; D053482:beta 2-Glycoprotein I / Q000276:immunology
chemical_list: D001323:Autoantibodies; D016682:Lupus Coagulation Inhibitor; D010980:Platelet Membrane Glycoproteins; D053482:beta 2-Glycoprotein I