Description
Biological activity
Background information
Interleukin 21 (IL-21) is a four α-helix bundle cytokine and closely related to IL-2, IL-4, and IL-15. IL-21 expression is restricted to activated CD4+ T helper cells and NKT cells. Among T helper subsets, IL-21 is strongly produced by follicular T helper cells and TH17 cells, where IL-21 serves as an autocrine regulator and seems to sustain TH17 development. The functional receptor for IL-21, composed of the IL-21 receptor- and the common γ-chain, is expressed on various hematopoietic cells including T, B, NK, and dendritic cells. Accordingly, IL-21 exerts pleiotropic effects on both cellular and humoral immune responses, such as stimulation of lymphocyte proliferation, promotion of CD8+ T cell and NK cell cytotoxicity, and differentiation of B cells into plasma cells. Important roles for IL-21 have been proposed with regard to its anti-tumor activity and for the development of autoimmune diseases.
Quality description
Research-grade cytokines are suitable for a wide variety of cell culture applications. They are sterile-filtered prior to lyophilization. Generally, endotoxin levels are <0.1 ng/μg (<1 EU/μg), and purities are >95%. The biological activity is tested in appropriate bioassays.
Premium-grade cytokines offer the convenience of high and well-defined biological activities and allow exact unit dosing for demanding applications. The biological activity is determined after lyophilization and reconstitution, and normalized to WHO/NIBSC standards whenever available. In general, endotoxin levels are <0.01 ng/μg (<0.1 EU/μg), and purities are >97%. Lot-specific activities are stated in the Certificate of Analysis (www. miltenyibiotec.com/certificates).
Overview
Recombinant human IL-21 (interleukin 21) can promote differentiation of TH17 or T follicular helper (Tfh) cells, expansion of CD8+ T cells, as well as B and NK cell development. Thus, the pleiotropic cytokine regulates several aspects of lymphoid cell function and has central roles for humoral immunity. IL-21 has been associated with allergies, cancer, and viral infections. Recombinant protein human IL-21 was developed for use in various applications, such as cell culture, differentiation studies, and functional assays.
