Interleukin-2 (IL-2) is a T cell stimulatory cytokine that induces T cell proliferation and NK cell proliferation and activation. Produced by T-cells in response to antigenic or mitogenic stimulation, this protein is required for T-cell proliferation and other activities crucial to regulation of the immune response. Can stimulate B-cells, monocytes, lymphokine-activated killer cells, natural killer cells, and glioma cells. The receptor of this cytokine is a heterotrimeric protein complex whose gamma chain is also shared by interleukin 4 (IL4) and interleukin 7 (IL7). IL-2 induces CTLA-4 and also functions as a survival factor for lymphocytes.