Purity >95% as determined by SDS-PAGE. Interleukin 2 (IL-2) is an immunomodulatory cytokine that is produced by lymphocytes. IL-2 signals through the IL-2R receptor to induce activated T cell proliferation and promote T cell differentiation. IL-2 also stimulates the proliferation and differentiation of B cells, natural killer cells, monocytes, and macrophages.