CCL18 and cancer: TAMs and MDSCs are thought to be major orchestrators of the immunological properties of solid tumors because they i) secrete immunosuppressive cytokines such as TGF-β and IL-10 (3), ii) express checkpoint receptors (e.g. PD-L1) that inhibit effector functions (40), iii) release growth factor such as VEGF, PDGF, and FGF that promote cancer cell and neovasculature proliferation (41, 42), and iv) discharge chemokines (e.g. CCL18) and cytokines (e.g. TGFβ) that recruit fibroblasts and enhance tumor proliferation (4, 43).