title: Clinical significance of anti-domain 1 β2-glycoprotein I antibodies in antiphospholipid syndrome.
abstract: BACKGROUND
  Antiphospholipid syndrome (APS) is characterized by the presence of circulating antiphospholipid antibodies (aPL) in patients with thrombosis and/or pregnancy morbidity. In APS patients anti-domain 1 β2-glycoprotein I (anti-D1 β2GPI) IgG antibodies correlate strongly with thrombosis and to the lesser extent, with pregnancy complications. The aim of this study was to assess clinical utility of the anti-D1 β2GPI antibodies in the diagnosis and risk stratification of antiphospholipid syndrome.
  
  
  METHODS
  In this retrospective study 202 autoimmune patients were studied (primary APS - 58, secondary - 45 SLE - 99). Anticardiolipin (aCL) and anti-β2GPI (aβ2GPI antibodies) (IgG and IgM class) together with anti-D1 IgG were tested with QUANTA Flash chemiluminescent immunoassay and lupus anticoagulant (LA) with coagulometric methods.
  
  
  RESULTS
  The highest anti-D1 values were observed in triple positive patients as compared to patients with other antiphospholipid antibody profiles. A strong correlation was found between levels of anti-D1 IgG and a β2GPI IgG antibodies for all patients analyzed (Spearman's ρ=0.87; p<0.0001). Anti-D1 IgG antibodies increase specificity resulting from classic aPL positivity but at the expense of sensitivity. Anti-D1 test does not add accuracy in predicting APS thrombotic complications on the top of accuracy offered by classic aPL tests and their profiles.
  
  
  CONCLUSIONS
  Anti-D1 IgG antibodies did not add diagnostic power to the standard laboratory aPL tests as assessed by this retrospective study. A true clinical significance of anti-D1 antibodies in thrombotic risk stratification of aPL positive patients will require a properly designed clinical prospective trials.
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Teresa
authors.initials: T
authors.lastname: Iwaniec
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Marcin P
authors.initials: MP
authors.lastname: Kaczor
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Celińska-Löwenhoff
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Polański
authors.affiliation: Department of Medicine, Jagiellonian University Medical College, Kraków, Poland. Electronic address: mmmusia@cyf-kr.edu.pl.
authors.forename: Jacek
authors.initials: J
authors.lastname: Musiał
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017153:Antibodies, Anticardiolipin / Q000276:immunology; D017152:Antibodies, Antiphospholipid / Q000276:immunology*; D016736:Antiphospholipid Syndrome / Q000150:complications* / Q000175:diagnosis / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D016682:Lupus Coagulation Inhibitor / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013927:Thrombosis / Q000175:diagnosis / Q000209:etiology* / Q000276:immunology; D055815:Young Adult; D053482:beta 2-Glycoprotein I / Q000276:immunology*
chemical_list: D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I
keywords: Anti-D1 β(2)GPI IgG antibodies; Antiphospholipid antibodies; Antiphospholipid syndrome; Thromboembolic risk