TREM2 and neoplasm: In non-small cell lung cancer (NSCLC), TREM2 expressed on monocyte-macrophages can not only block IL-18 production and signaling by enhancing interleukin (IL)-18/IL- 18bp decoy interactions, but also inhibit IL-15 production by DCs, which in turn inhibits NK cell recruitment and activation, suppresses NK cell-mediated anti-tumor immunity, and prevents NK cells from effectively killing tumor cells (36).