Description
L15 has been shown to be produced by human fetal astrocytes and microglial cells in response to IL1- beta, IFN-gamma, or TNF- alpha and may thus play a role in T-cell mediated immune responses in the human central nervous system. IL15 stimulates proliferation of the established T-cell line CTLL-2, CD8 (+) memory T- cells require IL15 for proliferation.IL15 is also able to induce generation of cytolytic cells and LAK cells activity in vitro. IL15 appears to function as a specific maturation factor for NK-cells and can mimic the bone marrow microenvironment in vitro, which is required for NK- cells to acquire lytic functions. L15 induces proliferation of mast cells in the absence of functional IL2 receptor components and utilizes a receptor of 60-65 kDa that is distinct from known components of T-cell IL15 receptors. The IL15 receptor on mast cells recruits JAK2 and STAT5, instead of JAK1, JAK3 and STAT3 and STAT5 that are activated in T- cells. The alpha subunit of the IL15 receptor (IL15RA) is structurally related to the alpha subunit of the IL2 receptor and confers high affinity binding of IL15 to its receptor. IL15 binds to the beta and gamma chains of the IL2 receptor, which are known to be required for ligand internalization and signal transduction