Implication of molecular analysis of HLA-A*02 subtyping for unrelated bone-marrow donor selection

The HLA-A*02 allele is the most heterogeneous allele at HLA-A locus with 22 different subtypes so far identified. All of these subtype polymorphisms are located in alpha 1 and alpha 2 domains which are responsible for peptide biding and HLA restricted recognition by T-cell receptor. The aim of the present study was to determine the frequency of different HLA-A*02 alleles in 33 healthy unrelated Croatians. HLA-A*02 subtyping has also been retrospectively performed in 2 recipient-unrelated donor pairs and in 4 recipient-HLA phenotypically identical parent pairs. All subjects, previously typed as HLA-A2 by serology were tested using HLA-A*02 ARMS-PCR kit which discriminates 17 different A*02 alleles. Among 17 A*02 alleles we have found 4 different A*02 subtypes in healthy unrelated Croatians. The most frequent A*02 allele was A*0201 (84%). The frequency of the remaining A*02 alleles were as follows: A*0205 (3%), A*0207 (6%) and A*0213 (6%). Among 6 tested bone-marrow transplantation (BMT) pairs, only one has been found to be A*02 subtype incompatible (A*0201/A*0205). Four different A*02 alleles are found in Croatian population with the predominance of A*0201. However these results suggest that A*02 subtyping is also necessary for optimal matching of HLA-A*02 positive donor-recipient pairs in HLA incompatible BMT.