Homozygous status for HLA-E0103 confers protection from acute graft-versus-host disease and transplant-related mortality in HLA-matched sibling hematopoietic stem cell transplantation

The posttransplant period following hematopoietic stem cell transplantation (HSCT) is potentially high risk for developing survival-compromising complications, many of which are known to be under the control of immunogenetic factors. Given the dual role of human leukocyte antigen (HLA)-E molecules in innate and adaptive immune processes, we analyzed the impact of HLA-E polymorphism in genoidentical HSCT setting. We analyzed 187 HLA-genoidentical sibling pairs for HLA-E polymorphism. To explore its potential association with the incidence of acute and chronic graft versus host disease (aGVHD, cGVHD), severe infections, risk for transplant-related mortality (TRM), and overall survival, HLA-E locus was genotyped by a polymerase chain-reaction-sequence-specific primer (PCR-SSP) strategy. Multivariate analysis, taking into account the patient-, donor- and transplant-related factors, showed that the incidence of aGVHD and TRM at day 180 were low when the genotype was HLA-E*0103/E*0103, either in the donor or in the recipient, the pairs being identical for HLA-E alleles (hazard ratio [HR]=0.71, P=0.009; and HR=0.42, P=0.04, respectively). We also found a trend towards association between E*0103 homozygosity and improved survival (P=0.05). There was no association between HLA-E polymorphism and incidence of severe infections. These data suggest that the homozygous state for HLA-E*0103 allele behaves as a protective genetic factor against aGVHD and TRM and likely contributes to improved survival in HLA-genoidentical bone marrow transplantation.