Abstract
NK cell receptor (NKR)-expressing cells have cytolytic activity against leukemic cells, while solid tumor cells escape from T cell recognition because of the low expression level of HLA class I molecules in both allogenic and autologous settings. This characteristic nature of NK cells, recognition of target cells in contrast with T cells, provides a strategy to overcome tolerance in the tumor-bearing host. Furthermore, donor alloreactive NK cells, which are induced by killer cell immunoglobulin-like receptor (KIR) ligand incompatibility between donor and recipient HLA class I in the graft-versus-host (GVH) direction, can attack leukemic cells and host antigen-presenting cells (APC), resulting in the enhancement of graft-versus-leukemia (GVL) effect and the suppression of graft-versus-host disease (GVHD) at the same time. Therefore, NK cells may play an important role on the regulation of GVHD and GVL. In addition, NK cell therapy may be a promising treatment against leukemia and solid cancers which escape from T cell immune surveillance.
