Frequency of human platelet antigens (HPA)-1, -2, -5 and -15 in Brazilian blood donors and establishment of a panel of HPA-typed donors.

OBJECTIVES: The aim of this study is to keep a record of regular human platelet antigens (HPA)-typed blood donors and to compare their allele frequencies with those reported in other populations.

BACKGROUND: HPA are polymorphisms expressed on platelet membrane glycoproteins. They can generate an immune response leading to platelet alloimmunisation that may show clinical manifestations, such as neonatal alloimmune thrombocytopenia, post-transfusion purpura and platelet refractoriness. Platelet alloimmunisation is not uncommon, therefore, for an optimum management, it is advantageous to establish a panel of typed platelets to help matched platelets selection in HPA-alloimmunised patients transfusion.

METHODS: The polymerase chain reaction (PCR)-allele-specific primers and PCR-restriction fragment length polymorphism methods were used to determine the genotypes of HPA-1, -2, -5 and -15 systems of 337 blood donors.

RESULTS: The three genotypes (AA, AB and BB) were found in all HPA systems analysed, and the most frequent genotypes were AA for HPA-1, -2 and -5 systems (mean: 0·732) and AB for HPA-15 system (mean: 0·523). Allele frequencies were 0·148, 0·155, 0·140 and 0·430 for HPA-1b, -2b, -5b and -15b, respectively, and they were similar to those found in Caucasian populations, especially for HPA-1. However, the B allele was more frequent in all HPA systems when compared with Amazon Indians, and the frequency of the B allele in our study was higher in HPA-1 and -15 systems and lower in HPA-2 and -5 systems in comparison with sub-Saharan African populations.

CONCLUSIONS: A record of HPA-typed donors would enable rapid identification and selection of donors when HPA-compatible platelets are required for transfusion.