Interleukin-21 (IL-21) belongs to the Type I four helix bundle cytokines, and shares the common cytokine receptor ? chain with IL-2, IL-4, IL-7, IL-9, and IL-15. IL-21 is expressed by CD4+ T cells, natural killer (NK) T cells, and Th17 cells. The IL-21 receptor is highly expressed on CD4+ and CD8+ B cells. IL-21 plays a pivotal role in the survival and proliferation of B cells, and their differentiation to immunoglobulin (Ig) producing cells. IL-21regulates the production of IgG1 and IgE by B cells, and diminishes the severity of allergy and asthma. In some cases, IL-21 induces B cell apoptosis. Other roles of IL-21 include regulation of the innate immune system, implication in autoimmunity, and antitumor activity.
Recombinant mouse interleukin-21 (IL-21) produced in E.coli is a single non-glycosylated polypeptide chain containing 130 amino acids. A fully biologically active molecule, rhIL-21 has a molecular mass of 15.1 kDa analyzed by reducing SDS-PAGE and is obtained by chromatographic techniques at GenScript.