IL-15 is a member of the four α-helix bundle cytokine family. It is produced by different cell types, including epithelial cells, monocytes, muscle, and placenta cells. IL-15 is a potent lymphoid cell growth factor and shares many biological properties with IL-2. Like IL-2, IL-15 stimulates the proliferation of activated T cells and promotes the generation of cytotoxic T lymphocytes (CTLs). IL-2 and IL-15 also induce the generation, proliferation, and activation of NK cells as well as B cell growth and immunoglobulin production. In addition, IL-15 is important for the maintenance of CD8

memory T cells. For binding and signaling IL-15 uses the unique IL-15 receptor α-chain, but shares the β- and γ-chain of the IL-2 receptor.

cytokines are suitable for a wide variety of cell culture applications. They are sterile-filtered prior to lyophilization. Generally, endotoxin levels are <0.1 ng/μg (<1 EU/μg), and purities are >95%. The biological activity is tested in appropriate bioassays.