Clinical significance of donor-recipient HLA matching on survival after myeloablative hematopoietic cell transplantation from unrelated donors.

The application of unrelated donor hematopoietic cell transplantation can be expanded with the use of mismatched donors if human leukocyte antigen (HLA) disparity does not lead to increased morbidity and mortality. The rules that govern permissibility of HLA mismatches are not well defined. The International Histocompatibility Working Group in hematopoietic cell transplantation measured the risks associated with locus-specific disparity in 4796 patients transplanted for low, intermediate, or high-risk hematologic diseases. The permissibility of a given HLA mismatch is in part defined by the locus and by disease risk.