CCL17 and neoplasm: M2 macrophages are generally considered to be the phenotype of tumor-associated macrophages (TAMs),454–456 have immunosuppressive and angiogenesis-promoting effects, and are considered to be a tumor-promoting cell type.456,457 M2 macrophages secrete CCL17 (C-C chemokine ligand 17), CCL22, and CCL24 and have low expression of IL-12 and high expression of IL-10.