Collaborative studies to establish the first World Health Organization International Standard for detection of human antibody against human platelet antigen-3a

Vox Sang. 2007 Nov;93(4):309-15. doi: 10.1111/j.1423-0410.2007.00899.x.

Abstract

Background and objectives: The platelet-specific antibody anti-human platelet antigen-3a (anti-HPA-3a) is involved in neonatal alloimmune thrombocytopenia, post-transfusion purpura, and platelet refractoriness. However, HPA-3a antibodies are often difficult to detect, probably because the antigen is labile. This report describes the production of a freeze-dried preparation of pooled human plasma, coded 03/190, containing IgG antibodies against the HPA-3a. The material is intended for use as a minimum sensitivity reagent in glycoprotein-specific assays currently used for anti-HPA-3a detection. Laboratories can use it to assess the sensitivity of their 'in-house' assays for anti-HPA-3a and to calibrate local controls for routine use in each batch of tests.

Materials and methods: Plasma containing anti-HPA-3a was obtained from a mother of two babies both born with severe thrombocytopenia, and following dilution it was freeze dried in glass ampoules.

Results: Two collaborative studies demonstrated that the candidate material contained anti-HPA-3a and human leucocyte antigen (HLA) class I antibodies, but no other HPA antibodies that might confuse the detection of the anti-HPA-3a. The minimum dilution that should give a positive result was determined to be 1 : 8 by two further international collaborative studies involving a total of 49 laboratories in 23 countries.

Conclusion: The material also contains HLA antibodies and is suitable for use only in techniques that are glycoprotein specific (i.e. monoclonal antibody immobilization of platelet antigens and enzyme-linked immunosorbent assay) where only HPA antibodies will be detected. This standard will allow laboratories to measure their sensitivity of detection of anti-HPA-3a and will also allow those laboratories with relatively insensitive techniques to monitor their performance as they improve their methodology.

MeSH terms

  • Antigens, Human Platelet / immunology*
  • Blood Banking / methods*
  • Cooperative Behavior
  • Humans
  • Immunoassay / methods*
  • Isoantibodies / analysis
  • Isoantibodies / blood*
  • Reference Standards
  • Sensitivity and Specificity

Substances

  • 3a alloantigen, human
  • Antigens, Human Platelet
  • Isoantibodies