Description: Interleukin-21 (IL-21) is a cytokine secreted by activated CD4+ T cells. Its molecular structure is similar to IL-15. IL-21 plays a role in regulating B cell proliferation and, in conjunction with IL-15, promotes the proliferation of bone marrow precursor cells and the proliferation, differentiation, and cytotoxic activity of NK cells. IL-21 enhances CD40-mediated proliferation while inhibiting proliferation induced by anti-immunoglobulin M (IgM) and IL-4. IL-21 is an immunosuppressive factor that acts on B cells and can inhibit the proliferation of B cell lymphoma cell subsets. It may also play a role in regulating B cell tumorigenesis. This product is derived from a mammalian cell expression system (HEK293) containing the gene for human IL-21, which is fermented, isolated, highly purified, and then lyophilized. Source: HEK293