Interleukin (IL)-15 is a pleiotropic cytokine that plays a pivotal role in both innate and adaptive immunity. IL-15 is unique among cytokines due to its participation in a trans signaling mechanism in which IL-15 receptor alpha (IL-15R alpha) from one subset of cells presents IL-15 to neighboring IL-2R beta/gamma(c)-expressing cells. This newly discovered cytokine is produced by a wide variety of cells and tissues and like IL-2, stimulates the proliferation of T-lymphocytes and induces the generation of cytotoxic T-lymphocytes (CTLs) and lymphokine-activated killer (LAK) cells. Recombinant protein corresponding to aa49-162 of human IL-15, expressed in E. coli. Molecular Weight: ~13.9kD (123aa) confirmed by MALDI-TOF Biological Activity: Measured in a cell proliferation assay using CTLL2 mouse cytotoxic T cells. The ED50 for this effect is <1ng/ml. Amino Acid Sequence: MNWVNVISDL KKIEDLIQSM HIDATLYTES DVHPSCKVTA MKCFLLELQV ISLESGDASI HDTVENLIIL ANNSLSSNGN VTESGCKECE ELEEKNIKEF LQSFVHIVQM FINTSLEHHH HHH Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.