Interleukin-2(IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system，belongs to the IL-2 family. It is a powerful immunoregulatory lymphokine produced by T-cells in response to antigenic or mitogenic stimulation. IL-2/IL-2R signaling is required for T-cell proliferation and other fundamental functions that are essential for the immune response. IL-2 stimulates growth and differentiation of B-cells, NK cells, lymphokine-activated killer cells, monocytes, macrophages and oligodendrocytes. New research has shown that IL-2 mutant reduced toxicity while being more potent at stimulating anti-tumor effector immune cells.