HLA-B44 subtyping in the Catalan population using reference strand mediated conformation analysis. Implications for the selection of unrelated bone marrow donors

Cytotoxic T lymphocytes (CTLs) reactive against the disparity between HLA-B *4402 and HLA-B*4403 have been reported after unrelated donor bone marrow t ransplantation. These CTLs have been associated with acute graft-versus-hos t disease and graft rejection. This study describes the HLA-B44-subtyping i n the Catalan population using reference-strand mediated conformation analy sis. It has been performed on 297 unrelated HLA-B44+ cord blood units from the Barcelona Cord Blood Bank (Barcelona, Spain). We have found a predomina nce of HLA-B*4403 (66.04%) over HLA-B*4402 (33.02%), whereas the predominan t HLA-B44 allele in Northern Europe and the United States is HLA-B*4402. Th is inverted proportion between HLA-B44 subtypes in Mediterranean population s compared with other Caucasian populations suggests that HLA-B44 subtyping should be performed when an HLA-B44+ unrelated donor marrow is identified.