The particles contain a firefly luciferase gene driven by the human IL-2 promoter (Figure 1). After transduction, activation of the IL-2 signaling pathway in the target cells can be monitored by measuring the luciferase activity.

IL-15 has been shown to be produced by human fetal astrocytes and microglial cells in response to IL-1beta, IFN-gamma, or TNF- alpha and may thus play a role in T-cell mediated immune responses in the human central nervous system. IL-15 stimulates proliferation of the established T-cell line CTLL-2, CD8(+) memory T- cells require IL-15 for proliferation. IL-15 is also able to induce generation of cytolytic cells and LAK cells activity in vitro. IL-15 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. IL-15 induces proliferation of mast cells in the absence of functional IL-2 receptor components and utilizes a receptor of 60-65 kDa that is distinct from known components of T-cell IL-15 receptors. The IL-15 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 IL-15 receptor (IL-15RA) is structurally related to the alpha subunit of the IL-2 receptor and confers high affinity binding of IL-15 to its receptor. IL-15 binds to the beta and gamma chains of the IL2 receptor, which are known to be required for ligand internalization and signal transduction.

Figure 1. Dose Response of Recombinant HumanlL15 in hlL2IL15 Dual Effector(mCD25hCD122mCD132) Reporter Cells.

Figure 2. Dose Response of Recombinant Human lL2 in hIL2/IL15 Dual Effector (mCD25hCD122mCD132) Reporter Cells (C31).