Interleukin-15 (IL15), also designated IL-T, is a cloned cytokine which shares several biological activities but no sequence homology with IL2. IL15 stimulates the proliferation of T cells and NK cells, while enhancing B cell expansion and antibody production. Unlike IL2, IL15 is not produced by lymphocytes, but appears to be produced by macrophages, epithelial lines, muscle and placenta. IL15 has also been shown to be a chemoattractant for human blood T lymphocytes and to be able to induce lymphokine-activated killer (LAK) activity in NK cells as well as to be able to induce the generation of cytolytic effector cells. Studies have shown that IL15 is the only other cytokine that shares the β signaling subunit of the IL2R.
