KIR3DL1 and graft versus host disease: Besides, KIR expression on NK cells may be higher when T cells are depleted in the graft (32), which may be due to the loss of cytokines competitors of NK cells after T lymphocyte removal (33), thus accelerating the maturation of NK cells and intensifying NK cell cytotoxicity towards T cells and APCs in the recipient, leading to GVHD suppression.