Flow cytometry immunophenotyping and polymerase chain reaction-site-specific primers genotyping for HPA-1 alloantigens in an Italian blood donor population.

BACKGROUND AND

OBJECTIVES

There is increasing interest in the development of rapid and reliable techniques for human platelet alloantigen (HPA) typing. This study investigates the reliability of flow cytometry for large-scale immunophenotyping of platelet alloantigens.

MATERIALS AND

METHODS

We used flow cytometry and polymerase chain reaction-site-specific primer (PCR-SSP) for the characterization of the human platelet antigen 1 (HPA-1) mosaic in blood donors.

RESULTS

By using specific alloantisera and immunofluorescence labelling 9 (2.6%) out of 351 samples were HPA-1a-negative. To confirm this antigenic phenotype, all of the latter samples were submitted to PCR-SSP analysis, showing an HPA1-b/b genomic pattern. In HPA-1a-positive donors, flow cytometry was unable to distinguish HPA-1a/b heterozygous from HPA-1a/a homozygous subjects who were clearly identified by genotyping.

CONCLUSIONS

Flow cytometry is a valuable tool for large-scale screening to identify HPA-1a-negative persons, whereas genotyping is the assay of choice for zygosity testing, antenatal diagnosis, and for thrombocytopenic alloimmunized patients.