Impact of HLA-A, B, C allele mismatches on outcome after unrelated blood stem cell transplantation in whites

At our institution the selection of unrelated donors for hematopoietic stem cell transplantation (HSCT) relies on low resolution human leukocyte antigen (HLA)-A,B and high resolution HLA-DRB1,DQB1 DNA-based typing. To answer the question of whether routine high resolution HLA-A,B,C typing might improve HSCT outcome, 171 white "HLA-identical" donor/recipient pairs, as stated by our pretransplant tissue typing routine, were retyped for HLA-A,B,C using sequence based typing (SBT). The numbers of HLA-A,B,C allele mismatches detected by SBT were correlated to established clinical endpoints of HSCT outcome. We found 33.9% of the study transplants to be fully HLA-A,B,C matched, whereas 66.1 % exhibited one through four donor/recipient HLA-A,B,C allele mismatches. However, statistical analysis could not demonstrate an impact of the number of HLA-A,B,C allele mismatches on overall survival and other analyzed endpoints. Thus, our series of white donor/recipient pairs does not suggest the routine use of HLA-A,B,C SBT to improve HSCT outcome substantially.