AUTHOR=Borghi Maria Orietta , Beltagy Asmaa , Garrafa Emirena , Curreli Daniele , Cecchini Germana , Bodio Caterina , Grossi Claudia , Blengino Simonetta , Tincani Angela , Franceschini Franco , Andreoli Laura , Lazzaroni Maria Grazia , Piantoni Silvia , Masneri Stefania , Crisafulli Francesca , Brugnoni Duilio , Muiesan Maria Lorenza , Salvetti Massimo , Parati Gianfranco , Torresani Erminio , Mahler Michael , Heilbron Francesca , Pregnolato Francesca , Pengo Martino , Tedesco Francesco , Pozzi Nicola , Meroni Pier Luigi 

TITLE=Anti-Phospholipid Antibodies in COVID-19 Are Different From Those Detectable in the Anti-Phospholipid Syndrome

JOURNAL=Frontiers in Immunology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.584241

DOI=10.3389/fimmu.2020.584241

ISSN=1664-3224

ABSTRACT=<sec><title>Background</title><p>Critically ill patients with coronavirus disease 2019 (COVID-19) have a profound hypercoagulable state and often develop coagulopathy which leads to organ failure and death. Because of a prolonged activated partial-thromboplastin time (aPTT), a relationship with anti-phospholipid antibodies (aPLs) has been proposed, but results are controversial. Functional assays for aPL (i.e., lupus anticoagulant) can be influenced by concomitant anticoagulation and/or high levels of C reactive protein. The presence of anti-cardiolipin (aCL), anti-beta2-glycoprotein I (anti-β<sub>2</sub>GPI), and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies was not investigated systematically. Epitope specificity of anti-β<sub>2</sub>GPI antibodies was not reported.</p></sec><sec><title>Objective</title><p>To evaluate the prevalence and the clinical association of aPL in a large cohort of COVID-19 patients, and to characterize the epitope specificity of anti-β<sub>2</sub>GPI antibodies.</p></sec><sec><title>Methods</title><p>ELISA and chemiluminescence assays were used to test 122 sera of patients suffering from severe COVID-19. Of them, 16 displayed major thrombotic events.</p></sec><sec><title>Results</title><p>Anti-β<sub>2</sub>GPI IgG/IgA/IgM was the most frequent in 15.6/6.6/9.0% of patients, while aCL IgG/IgM was detected in 5.7/6.6% by ELISA. Comparable values were found by chemiluminescence. aPS/PT IgG/IgM were detectable in 2.5 and 9.8% by ELISA. No association between thrombosis and aPL was found. Reactivity against domain 1 and 4-5 of β<sub>2</sub>GPI was limited to 3/58 (5.2%) tested sera for each domain and did not correlate with aCL/anti-β<sub>2</sub>GPI nor with thrombosis.</p></sec><sec><title>Conclusions</title><p>aPL show a low prevalence in COVID-19 patients and are not associated with major thrombotic events. aPL in COVID-19 patients are mainly directed against β<sub>2</sub>GPI but display an epitope specificity different from antibodies in antiphospholipid syndrome.</p></sec>