Brain tumor cells can directly inhibit immune responses by regulating the expression of specific surface proteins, including programmed death-ligand 1 (PD-L1), cluster of differentiation 47 (CD47), human leukocyte antigen (HLA) molecules and natural killer group 2 member D (NKG2D) ligands, or indirectly through the secretion of anti-inflammatory cytokines or chemokines promoting the recruitment of immunosuppressive cells such as tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC), which constitute up to 50% of the glioma mass [14]. The gene discussed is KLRK1; the disease is neoplasm.