Loss-Prone HLA Class I Alleles Inform Outcomes of Early Hematopoietic Cell Transplantation in Acquired Aplastic Anemia.

HLA class I allele loss in acquired aplastic anemia (AA) represents an immune escape from the T cell-mediated pathogenesis. We investigated the impact of loss-prone HLA alleles on the hematopoietic cell transplantation (HCT) outcomes using registry data of 875 Japanese patients with acquired AA. HLA associations were evident exclusively among 399 patients who received HCT within 1 year of the diagnosis, consistent with the predominance of HLA loss in this group.