Interleukin 2 (IL-2) is a protein that occurs naturally in your body. It plays an important role in "switching on" or activating the body's immune system. IL-2 activates special defense cells called "T cells" and "natural killer (NK) cells," to attack and destroy invading germs or diseases.
IL-2 can also stimulate T cells and NK cells to attack and destroy cancer cells. A man-made version of IL-2, called aldesleukin, is available. It acts like natural IL-2 to help the immune system recognize and destroy certain types of melanoma. This treatment is only meant for patients with advanced melanoma (Stage IV) that has spread far from the original site, or to other organs (such as the lungs or liver).