M2 macrophages and TAMs have protumor and immune inhibitory effects, secrete large amounts of IL-10, TGF-β, C-C motif chemokine ligand 17 (CCL17), and CCL22, attract noncytotoxic Treg and type II T-helper cells (TH2 cells) to aggregate in tumor tissues, inhibit T-cell differentiation and functions, lower cytotoxic T-cell function, induce T-cell apoptosis, secrete CCL18, and attract naïve T cell [10, 16, 32, 35]. This evidence concerns the gene CCL17 and neoplasm.