title: A multicenter validation of recombinant β3 integrin-coupled beads to detect human platelet antigen-1 alloantibodies in 498 cases of fetomaternal alloimmune thrombocytopenia.
abstract: BACKGROUND
  Fetomaternal alloimmune thrombocytopenia (FMAIT) is caused by human platelet (PLT) antigen (HPA) incompatibility. Beads coupled with recombinant β3 integrins, displaying the biallelic HPA-1 epitopes (rHPA-1), have been shown to detect HPA-1a alloantibodies implicated in FMAIT. This report describes a multicenter validation of the beads using the results of well-characterized samples to define the optimum parameters for analysis of a large cohort of 498 clinical samples.
  
  
  METHODS
  Fifty-one blinded quality assurance (QA) samples were tested by six laboratories to standardize the rHPA-1 bead assay and to develop an algorithm for sample classification. Five laboratories retrieved samples from 498 independent FMAIT cases, previously tested by the monoclonal antibody-specific immobilization of PLT antigens (MAIPA) assay, from their local archives for testing with the rHPA-1 beads. The results were evaluated using a mathematical algorithm developed to classify the samples.
  
  
  RESULTS
  The QA samples gave a mean concordance of 94% between the bead and MAIPA assays, while 97% concordance was observed with the FMAIT samples. Of the 15 discrepant samples, seven were positive by the beads but negative by MAIPA, while the contrary was observed for eight samples. Overall, the bead assay achieved 98% sensitivity for HPA-1a antibody detection in FMAIT and 98.7% specificity compared to the local MAIPA.
  
  
  CONCLUSIONS
  The rHPA-1 bead assay is a rapid 3-hour assay for the sensitive detection of HPA-1 antibodies. Its ease of use would enable prompt detection of maternal HPA-1a antibodies in suspected FMAIT cases, which is important supportive evidence for treatment by transfusion with HPA-1b1b PLTs.
authors.affiliation: Histocompatibility and Immunogenetics Laboratories, National Health Service Blood and Transplant (NHSBT), Colindale, London, UK.
authors.forename: Winnie
authors.initials: W
authors.lastname: Chong
authors.affiliation: Department of Haematology, University of Cambridge and NHSBT Cambridge, Cambridge Biomedical Campus.|Medical Research Council Biostatistics Unit, Cambridge Biomedical Campus, Cambridge, UK.
authors.forename: Ernest
authors.initials: E
authors.lastname: Turro
authors.affiliation: National Institute for Biological Standards and Control Medicines and Healthcare Products Regulatory Agency, Potters Bar, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Metcalfe
authors.affiliation: National Institute for Biological Standards and Control Medicines and Healthcare Products Regulatory Agency, Potters Bar, UK.
authors.forename: Rizwan
authors.initials: R
authors.lastname: Yusuf
authors.affiliation: Etablissement Français du Sang Rhône-Alpes (EFS), Lyon, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Mérieux
authors.affiliation: Etablissement Français du Sang Rhône-Alpes (EFS), Lyon, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Rigal
authors.affiliation: Platelet and Leukocyte Serology Department, Sanquin Diagnostic Services, Amsterdam, the Netherlands.
authors.forename: Leendert
authors.initials: L
authors.lastname: Porcelijn
authors.affiliation: Platelet and Leukocyte Serology Department, Sanquin Diagnostic Services, Amsterdam, the Netherlands.
authors.forename: Elly
authors.initials: E
authors.lastname: Huiskes
authors.affiliation: Histocompatibility and Immunogenetics Laboratories, National Health Service Blood and Transplant (NHSBT), Filton, Bristol, UK.
authors.forename: Geoff
authors.initials: G
authors.lastname: Lucas
authors.affiliation: Histocompatibility and Immunogenetics Laboratories, National Health Service Blood and Transplant (NHSBT), Filton, Bristol, UK.
authors.forename: Nina
authors.initials: N
authors.lastname: Bendukidze
authors.affiliation: Histocompatibility and Immunogenetics Laboratories, National Health Service Blood and Transplant (NHSBT), Filton, Bristol, UK.
authors.forename: Ann
authors.initials: A
authors.lastname: Green
authors.affiliation: Hospital Sirio Libanês Blood Bank, São Paulo, Brazil.
authors.forename: Rita
authors.initials: R
authors.lastname: Fontão-Wendel
authors.affiliation: University Hospital North Norway, Tromso, Norway.
authors.forename: Anne
authors.initials: A
authors.lastname: Husebekk
authors.affiliation: International Blood Group Reference Laboratory (IBGRL), Filton, Bristol, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dixey
authors.affiliation: International Blood Group Reference Laboratory (IBGRL), Filton, Bristol, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Guest
authors.affiliation: International Blood Group Reference Laboratory (IBGRL), Filton, Bristol, UK.
authors.forename: Rosey
authors.initials: R
authors.lastname: Mushens
authors.affiliation: Department of Haematology, University of Cambridge and NHSBT Cambridge, Cambridge Biomedical Campus.
authors.forename: Willem H
authors.initials: WH
authors.lastname: Ouwehand
authors.affiliation: Histocompatibility and Immunogenetics Laboratories, National Health Service Blood and Transplant (NHSBT), Colindale, London, UK.|Division of Infection and Immunity, University College London, London, UK.
authors.forename: Cristina V
authors.initials: CV
authors.lastname: Navarrete
mesh_terms: D000465:Algorithms; D000483:Alleles; D016824:Antigens, Human Platelet / Q000276:immunology*; D005260:Female; D006801:Humans; D039661:Integrin beta3 / Q000235:genetics; D007518:Isoantibodies / Q000276:immunology*; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D054098:Thrombocytopenia, Neonatal Alloimmune / Q000276:immunology*
chemical_list: D016824:Antigens, Human Platelet; C061248:ITGB3 protein, human; D039661:Integrin beta3; D007518:Isoantibodies