Relationship of alloreactive NK cells to prognosis of HLA-identical sibling allogeneic hematopoietic stem cell transplantation

In recent years, the interaction between HLA class I alleles and receptors of NK cells have been paid more attention in HLA-identical sibling hematopoietic stem cell transplantation (HLA-identical sibling HSCT). NK cells mediate alloreactions when the allogeneic targets do not express HLA class I alleles that block inhibitory receptors of NK cells. Alloreactive donor-derived NK cells reduce GVHD by eliminating host-type antigen-presenting cells, but favor engraftment by killing host lymphocyte cells and reduce the risk of relapse by eradicating leukemia cells. Moreover, activating receptors also influence the outcome of HLA-identical sibling HSCT. In this review, the advance of the impact of both inhibitory and activating KIR (killer cell immunoglobulin-like receptor, KIR) on the outcome of HLA-identical sibling HSCT is briefly summarized.