IL-15 is a 4-?-helix bundle cytokine playing a pivotal role in stimulation of both innate and adaptive immune cells. It is produced primarily by keratinocytes, skeletal muscle cells, monocytes, and CD4+ T cells. It is a member of the common gamma chain family. The members of the common gamma chain family include the IL-2, IL-4, IL-7, IL-9, and IL-21 and require binding to the common ? chain receptor for activation. It can be used in growth and maintenance of T and NK cells. It is also shown to be used in proliferation and functional effect of T cells for adoptive cell therapy. It is a glycosylated protein and HumanKine IL-15 appear as 12.5-25 kDa bands (PMID: 24587813, 26627006, 27849617, 31250350)