title: A WHO reference reagent to standardize haemagglutination testing for anti-A and anti-B in serum and plasma: international collaborative study to evaluate a candidate preparation.
abstract: OBJECTIVE
  The aim of the study was to evaluate a lyophilized serum preparation, 14/300, for its suitability to serve as a World Health Organization (WHO) Reference Reagent to standardize and control haemagglutination titrations for anti-A and anti-B in serum and plasma, in an international collaborative study.
  
  
  METHODS
  Serum preparation 14/300 and two plasma-based reserve preparations, 14/304 (high titre anti-A) and 14/208 (high titre anti-B), were titrated by 24 laboratories in 13 countries using direct (DRT) and indirect (IAT) haemagglutination techniques.
  
  
  RESULTS
  There was eightfold to 64-fold variation in reported titres per preparation and method across laboratories, that is, titres extended over 4-7 dilutions, although intralaboratory variability was generally good, with over 90% of replicate titres within a twofold range. There was a reduction in interlaboratory variability when titres of the reserve preparations were adjusted relative to those of the candidate Reference Reagent.
  
  
  CONCLUSIONS
  The establishment of 14/300 as a WHO Reference Reagent for high titre anti-A and anti-B in serum, with nominal anti-A and anti-B titres of 128 for DRT, and nominal anti-A and anti-B titres of 256 for IAT, will facilitate global standardization of haemagglutination titrations for anti-A and anti-B in patient samples and blood components.
authors.affiliation: National Institute for Biological Standards and Control (NIBSC), Medicines and Healthcare Products Regulatory Agency, Potters Bar, Herts, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Thorpe
authors.affiliation: National Institute for Biological Standards and Control (NIBSC), Medicines and Healthcare Products Regulatory Agency, Potters Bar, Herts, UK.
authors.forename: B
authors.initials: B
authors.lastname: Fox
authors.affiliation: National Institute for Biological Standards and Control (NIBSC), Medicines and Healthcare Products Regulatory Agency, Potters Bar, Herts, UK.
authors.forename: G
authors.initials: G
authors.lastname: Sharp
authors.affiliation: UK NEQAS Blood Transfusion Laboratory Practice, Watford, UK.
authors.forename: J
authors.initials: J
authors.lastname: White
authors.affiliation: UK NEQAS Blood Transfusion Laboratory Practice, Watford, UK.
authors.forename: C
authors.initials: C
authors.lastname: Milkins
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology; D000906:Antibodies / Q000097:blood*; D006386:Hemagglutination Tests / Q000592:standards*; D006801:Humans; D007202:Indicators and Reagents; D007391:International Cooperation; D007753:Laboratories / Q000592:standards; D012015:Reference Standards; D014944:World Health Organization
chemical_list: D000017:ABO Blood-Group System; D000906:Antibodies; D007202:Indicators and Reagents
keywords: ABOi kidney transplantation; standardization; titrations