title: The introduction of anti-phosphatidylserine/prothrombin autoantibodies in the laboratory diagnostic process of anti-phospholipid antibody syndrome: 6 months of observation.
abstract: OBJECTIVE
  To evaluate the impact of the introduction of the anti-phosphatidylserine/prothrombin autoantibodies (aPS/PT) in the laboratory diagnostic process of anti-phospholipid antibody syndrome (APS).
  
  
  METHODS
  Four hundred and twenty-one patients (71.5 % females; 53 ± 15 years) presenting a medical prescription for aPS/PT antibodies were consecutively enrolled in the study from March 2013 to August 2013. During the same period, aPS/PT were additionally investigated in a selected series of 62 patients characterized by difficult lupus anticoagulant (LA) tests interpretation and in a retrospective series of 52 LA positive cases with available data about anti-prothrombin (aPT) antibodies. The aPS/PT antibodies, as well as the anti-cardiolipin (aCL), the anti-β2 glycoprotein I (aβ2GPI) and the aPT antibodies were analyzed by ELISA. LA was tested according to the recommended criteria, performing both the screen and the confirm steps.
  
  
  RESULTS
  Overall, aPS/PT IgM positive (>30 U/ml) and/or IgG frankly positive (>40 U/ml) antibodies were found in 49/421 (11.6 %) cases. Among the LA positive patients, we found 56.1 % aPS/PT positive versus 31.7 % aCL and/or aβ2GPI positive cases, with limited (17.1 %) simultaneous positivity. The PS/PT complex resulted the newly recognized specificity in about 27 % of patients recruited from the subset with difficult LA test interpretation. Compared to aPT antibodies, the aPS/PT antibodies displayed a much higher sensitivity (55.8 versus 15.4 %) in LA positive patients.
  
  
  CONCLUSIONS
  The introduction of aPS/PT antibodies in the diagnostic process of APS is highly recommended, since they disclose a notable diagnostic performance and a high correlation with LA activity, such that they can be a viable alternative.
authors.affiliation: Department of Laboratory Medicine, Institute of Clinical Pathology, University Hospital of Udine, Piazzale S. Maria Misericordia, 15, 33100 Udine, Italy ; Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Fabris
authors.affiliation: Department of Laboratory Medicine, Institute of Clinical Pathology, University Hospital of Udine, Piazzale S. Maria Misericordia, 15, 33100 Udine, Italy ; Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Giacomello
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Poz
authors.affiliation: Immunepathology and Allergy, Department of Laboratory Medicine, University Hospital of Udine, Udine, Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Pantarotto
authors.affiliation: Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Nicolanna
authors.initials: N
authors.lastname: Tanzi
authors.affiliation: Department of Laboratory Medicine, Institute of Clinical Pathology, University Hospital of Udine, Piazzale S. Maria Misericordia, 15, 33100 Udine, Italy ; Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Curcio
authors.affiliation: Immunepathology and Allergy, Department of Laboratory Medicine, University Hospital of Udine, Udine, Italy.
authors.forename: Elio
authors.initials: E
authors.lastname: Tonutti
keywords: Anti-beta2-glycoprotein I antibodies; Anti-cardiolipin antibodies; Anti-phosphatidylserine/prothrombin autoantibodies; Anti-phospholipid antibody syndrome; Lupus anticoagulant