Interleukin 15 (IL-15) is a widely expressed cytokine that is structurally and functionally related to IL-2. Mature human IL-15 shares 70% amino acid sequence identity with mouse and rat IL-15. Alternate splicing generates isoforms of IL15 with either a long or short signal peptide (LSP or SSP), and the SSP isoform is retained intracellularly. IL-15 binds with high affinity to IL-15Rα. It binds with lower affinity to a complex of IL2Rβ and the common gamma chain (γc) which are also subunits of the IL-2 receptor complex. IL-15 associates with IL15Rα in the endoplasmic reticulum, and this complex is expressed on the cell surface. The dominant mechanism of IL-15 action is known as transpresentation in which IL-15 and IL-15Rα are coordinately expressed on the surface of one cell and interact with complexes of IL2Rβ/γc on adjacent cells. This enables cells to respond to IL-15 even if they do not express IL-15Rα. Soluble IL-15 binding forms of IL-15Rα can be generated by proteolytic shedding or alternate splicing. These molecules retain the ability to bind tightly to IL-15 and can either inhibit or augment IL-15 function. Consistent with its shared use of IL-2 receptor subunits, IL-15 induces IL-2 like effects in lymphocyte development and homeostasis. It is particularly important for the maintenance and activation of NK cells and CD8+ memory T cells. IL-15 also exerts pleiotropic effects on other hematopoietic cells and nonimmune cells. Ligation of membrane associated IL-15/IL-15Rα complexes induces reverse signaling that promotes cellular adhesion, tyrosine phosphorylation of intracellular proteins, and cytokine secretion by the IL15/IL15Rα expressing cells. 仅供实验室使用。