Lupus
anticoagulants (LA) are a heterogeneous group of
antiphospholipid antibodies (aPLAs) that promote
thrombosis.
Tissue factor (TF)-bearing extracellular vesicles (EVs) might contribute to the prothrombotic state of patients with persistent LA and a history of
thrombosis. To investigate if EV-associated TF activity is elevated in a well-defined group of LA-positive patients with a history of
thrombosis in comparison to that of healthy controls. Adult patients (n = 94, median age 40.1 years, interquartile range (IQR) 29.9-53.4; 87% females) positive for LA and a history of
thrombosis (78%
venous thrombosis, 17% arterial
thrombosis, 5%
venous thrombosis and arterial
thrombosis) and healthy age- and sex-matched controls (n = 30, median age 42.9 years, IQR 38.6-45.8, 77% females) were included in this study. EV-TF activity was determined with
a factor Xa generation assay and anti-β2-glycoprotein (anti-β2GPI) and anticardiolipin (aCL)
antibodies by
enzyme-linked immunoassays. EV-TF activity did not differ between 94 LA-positive patients with a history of
thrombosis (median 0.05 pg/mL, IQR 0.00-0.14) and 30 healthy controls (median 0.06, IQR 0.00-0.11, p = 0.7745). No correlation was found between EV-TF activity and lupus-sensitive activated partial thromboplastin time (aPTT-LA) (rho = 0.034), Rosner index (rho = - 0.056), anti-β2GPI
IgG (rho = 0.05), anti-β2GPI
IgM (rho = - 0.08), aCL
IgG (rho = 0.12), and aCL
IgM (rho = - 0.11) in LA-positive patients. We found low EV-TF activity levels in LA-positive patients and a history of
thrombosis and no correlation with analyzed aPLAs. Our data indicate that circulating TF-bearing EVs do not contribute to the prothrombotic state of patients with LA.