KLRD1 and graft versus host disease: CAR-NK cell immunotherapy compared to the CAR-T cells has been shown to have advantages in safety (concerning reduced risk for graft-versus-host disease (GVHD), cytokine release syndrome (CRS), and neurotoxicity), in cytotoxic activity mechanisms (CAR-dependent and NK cell receptor-dependent mechanisms), and in “off-the-shelf” manufacturing (CAR-NK cells can be generated from multiple sources, including NK92 cell lines, PBMCs, umbilical cord blood (UCB), and induced pluripotent stem cells (iPSCs), eliminating the need for a patient-specific product) [79,81,82].