Human IL-15 protein

Interleukin-15 (IL-15) is a 14-15 kDa glycoprotein with immune regulatory functions in many diverse cell types. IL-15 can be constitutively expressed in a variety of cell types stored as intracellular protein in the cytoplasm as well as transport to the cell surface, while only secreted from some cell types including monocytes, dendritic cells, epithelial cells, bone marrow stromal cells, and fibroblasts. As a pleiotropic cytokine, IL-15 mediates the crosstalk between innate immunity and adaptive immunity whose principal role is to kill virally infected cells. IL-15 plays a crucial role in the development, differentiation, and survival of NK cells. In monocytes, IL-15 induces the production of IL-8 and monocyte chemotactic protein 1 (MCP-1), which recruits neutrophils and monocytes to sites of infection. IL-15 can also act as a chemo-attractant in T lymphocytes and regulate the differentiation of T lymphocytes.