title: Validation of a commercially available kit to detect anti-phosphatidylserine/prothrombin antibodies in a cohort of systemic lupus erythematosus patients.
abstract: BACKGROUND
  Antiprothrombin antibodies detection comprises two different ELISAs: prothrombin coated on irradiated plates (aPT) or phosphatidylserine/prothrombin (aPS/PT) as the antigen. While several commercial kits are available for the detection of aPT, aPS/PT are usually detected by in-house assays. Recently, a new commercially available kit was launched and, therefore, we decided to test its efficiency by comparing it to our in-house assay.
  
  
  METHODS
  aPS/PT were tested by our in-house assay (aPS/PT(ih)) in 75 SLE patients, using Immulon 1 plates coated with phosphatidylserine, purified human prothrombin and 1%BSA-TBS-CaCl as blocking and diluents. Data from this assay were compared to those obtained by the QUANTA Lite aPS/PT screen, IgG and IgM Elisa (INOVA Diagnostics, Inc, San Diego, USA) commercial kits (aPS/PT(c)).
  
  
  RESULTS
  aPS/PT were found in 41.3% and 46.7% of SLE patients by the aPS/PT(ih) and the aPS/PT(c), respectively. There was a positive correlation between IgG aPS/PT(ih) and aPS/PT(c) assays (R(2)=0. 861 by Spearman test, p=0.0027). Sensitivity and specificity for APS were 62.2% and 97.4% (AUC 0.780) for the aPS/PT(ih) assay and 70.3% and 84.2% (AUC 0.858) for the aPS/PT(C). Shorter running times were also seen when comparing the aPS/PT(ih) vs. aPS/PT(c) (7hours vs. 3hours, respectively).
  
  
  CONCLUSIONS
  The aPS/PT(C) is a reproducible and accurate test for the detection of aPS/PT, bringing also the advantage of shorter running times.
authors.affiliation: Graham Hughes Lupus Research Laboratory, Lupus Research Unit, The Rayne Institute, Division of Women's Health, King's College London.
authors.forename: Savino
authors.initials: S
authors.lastname: Sciascia
authors.affiliation: Louise Coote Lupus Unit, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, London, UK.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sanna
authors.affiliation: Graham Hughes Lupus Research Laboratory, Lupus Research Unit, The Rayne Institute, Division of Women's Health, King's College London.
authors.forename: Veronica
authors.initials: V
authors.lastname: Murru
authors.affiliation: Graham Hughes Lupus Research Laboratory, Lupus Research Unit, The Rayne Institute, Division of Women's Health, King's College London; Louise Coote Lupus Unit, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, London, UK.
authors.forename: Munther A
authors.initials: MA
authors.lastname: Khamashta
authors.affiliation: Graham Hughes Lupus Research Laboratory, Lupus Research Unit, The Rayne Institute, Division of Women's Health, King's College London. Electronic address: maria.bertolaccini@kcl.ac.uk.
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bertolaccini
mesh_terms: D000328:Adult; D017152:Antibodies, Antiphospholipid / Q000032:analysis* / Q000097:blood / Q000276:immunology; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology*; D008297:Male; D010718:Phosphatidylserines / Q000276:immunology*; D011237:Predictive Value of Tests; D011516:Prothrombin / Q000276:immunology*; D011933:Reagent Kits, Diagnostic / Q000592:standards*
chemical_list: D017152:Antibodies, Antiphospholipid; D015415:Biomarkers; D010718:Phosphatidylserines; D011933:Reagent Kits, Diagnostic; D011516:Prothrombin
keywords: QUANTA Lite™ aPS/PT; antiphospholipid syndrome; phosphatidylserine-prothrombin complex; prothrombin