IL2 and neoplasm: In the tumor microenvironment, there is an ongoing balance between the cytotoxic T lymphocytes (CTLs) that work to eliminate tumor cells through the secretion of cytokines including IFN-γ and IL-2, and the tumor cells themselves that can negatively regulate CTLs through the association with other immunosuppressive cells like myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and regulatory T cells (Tregs) [7].