The impact of HLA-E polymorphisms in graft-versus-host disease following HLA-E matched allogeneic hematopoietic stem cell transplantation.

The non-classical MHC class-I mainly involves in the regulation of innate immune responses where HLA-E plays a significant role in the cell identification by natural killer cells. HLA-E is a main regulatory ligand for natural killer cells and given the importance of these effector cells in hematopoietic stem cell transplantation, we investigated the effect of HLA-E polymorphisms on post-hematopoietic stem cell transplantation outcomes. The study group included 56 donor-patient pairs with underlying malignant hematological disorders undergoing HLA-E matched allogeneic hematopoietic stem cell transplantation. They were genotyped for HLA-E locus using a sequence specific primer-polymerase chain reaction. The median follow-up was 20.6 months (range 0.2-114.8) and the parameters assessed were acute and chronic graft-versus-host disease and overall survival. We showed a lower frequency of acute graft-versus-host disease (grade II or more; p=0.02) and chronic graft-versus-host disease (extensive; p=0.04) in the patients with HLA-E*0103/0103 genotype compared to other genotypes of HLA-E. There was also an association between HLA-E*0103/0103 and improved overall survival (p=0.001). Conclusively, our results suggest a protective role for HLA-E*0103/0103 genotype against acute graft-versus-host disease (grade II or more) and chronic graft-versus-host disease (extensive) as well as an association between this genotype and a better overall survival after HLA-E matched allogeneic hematopoietic stem cell transplantation.