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Scheme Description

Human Platelet Antigen’s (HPA) are polymorphic and can stimulate the production of HPA specific antibodies. HPA antibody detection/specification is important in several clinical situations, including neonatal alloimmune thrombocytopenia (NAIT), post-transfusion purpura (PTP) and cases of platelet transfusion refractoriness.



To assess participants’ ability to correctly detect the presence of and determine the specificity of HPA antibodies.



A total of eight serum/plasma samples will be sent each year as two distributions of four samples.



Participants are required to report the presence or absence of HPA antibodies in each sample. Participants are also required to report the HPA antibody specificities in samples designated as ‘positive’.

HLA antibody presence/absence results may also be reported.

Participants must only use the reporting forms provided within the UK NEQAS for H&I Participant’s Portal and are required to return results within 4 weeks.



Consensus presence of a specificity is determined by at least 75% of laboratories agreeing the presence of the specificity. Consensus absence of a specificity is determined by at least 95% of laboratories agreeing the absence of the specificity. Specificities failing to reach the consensus levels will not be assessed. The percent consensus for each specificity is calculated independently from other reported specificities.


Assessment Procedure

Assigning a consensus specificity – Acceptable

Missing a consensus specificity – Unacceptable

Assigning a specificity where the consensus is negative – Unacceptable

Each sample not reported – with valid reason – Not Assessed

Each sample not reported / late submission of results – Unacceptable


Satisfactory Performance

Satisfactory performance is testing eight samples and getting at least 75% of specificities in agreement with the consensus findings in a year.

Laboratories with unsatisfactory performance will receive written notification of their status and will be expected to reply to UK NEQAS for H&I detailing their corrective actions. For UK laboratories, unsatisfactory performance will be reported to UK NQAAP for Immunology. For UK laboratories, failure to reply or replies deemed unsatisfactory are likely to be further actioned by UK NQAAP for Immunology.


Information/Analysis Provided to Participants

  • Where known, the HPA types of the serum/plasma donors (for indication only).
  • Anonymised summary table of all participant results, comments and methodology. Including sample assessment result (acceptable/unacceptable classification) for each participant.
  • End of year summary of participant performance.