title: The clinical significance of autoantibodies directed against prothrombin in primary antiphospholipid syndrome.
abstract: BACKGROUND
  To evaluate the clinical significance of IgG/IgM antibodies directed against prothrombin (PT) in a homogeneous cohort of patients with primary APS (PAPS).
  
  
  METHODS
  IgG/IgM anti-prothrombin (aPT) antibodies were measured using a commercial ELISA kit in 158 PAPS patients and in 214 control subjects (100 healthy blood donors and 114 patients with autoimmune diseases).
  
  
  RESULTS
  IgG/IgM aPT antibodies were significantly associated with PAPS (OR, 95% CI: 52.0, 7.0-385.5; 9.8, 1.2-80.8, respectively). They were found to have a high specificity (IgG 99.50%, IgM 99.54%) but a low sensitivity (IgG 19.60%, IgM 3.80%) for PAPS. IgG aPT antibodies were significantly higher in the PAPS patients with thrombosis (OR, 95% CI: 69.2, 9.2-519.1) as well as in those with pregnancy morbidity alone (OR, 95% CI: 20.5, 2.4-174.5). The prevalence of IgG aPT was not significantly different in the thrombotic and obstetric patients, and the presence of IgM aPT antibodies was significant only in patients with thrombosis (OR, 95% CI: 2.6, 1.6-110.8).
  
  
  CONCLUSIONS
  The study's findings confirm that IgG/IgM aPT antibodies are significantly associated with PAPS and indicate that IgG aPT antibodies are associated with clinical subsets of the disease. For the time being, however, the lower sensitivity of IgG/IgM antibodies with respect to conventional aPL antibodies precludes their inclusion in the recommendations for the diagnosis of PAPS.
authors.affiliation: Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Padua, Padua, Italy. arielahoxha@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: Hoxha
authors.forename: A
authors.initials: A
authors.lastname: Ruffatti
authors.forename: M
authors.initials: M
authors.lastname: Pittoni
authors.forename: A
authors.initials: A
authors.lastname: Bontadi
authors.forename: M
authors.initials: M
authors.lastname: Tonello
authors.forename: E
authors.initials: E
authors.lastname: Salvan
authors.forename: M
authors.initials: M
authors.lastname: Plebani
authors.forename: L
authors.initials: L
authors.lastname: Punzi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016736:Antiphospholipid Syndrome / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011516:Prothrombin / Q000378:metabolism*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011516:Prothrombin