CD4 and neoplasm: TREM2 functions as a tumor suppressor and is predominantly expressed in various myeloid cell types, including dendritic cells (DCs), immunosuppressive macrophages, and monocytes. The absence of TREM2 facilitates the phenotypic transformation of macrophages towards the M1 phenotype, accompanied by the increased secretion of pro-inflammatory cytokines such as IL-12, IL-6, IL-15, and TNF. Notably, TREM2 deficiency also enhances the proliferation and activation of both CD8+ and CD4+ T cells [80]