CD4 and neoplasm: The immunosuppressive microenvironment is largely based on the presence of tumor-associated macrophages, mostly of the M2 phenotype and characterized by the secretion of anti-inflammatory cytokines IL-10 and TGF-β that inhibit the activity of Th1-polarized CD4+ and cytotoxic CD8+ T cells to initiate a cytolytic anti-tumor response while inducing the recruitment of regulatory Treg cells due to the release of chemokines like CCL2 and CCL22 [76].