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Description: Human Interleukin-21 (IL-21) is a 131-amino acid protein with 57% identity to the mouse gene. It contains a 24-amino acid signal peptide and a 4-helix-bundle cytokine domain homologous to IL-2, IL-4 and IL-15. IL-21 stimulates B cell proliferation in an anti-CD40 dependent manner but inhibits B cell proliferation stimulated by IL-4 plus anti-IgM. IL-21 is induced by IL-6 in activated T cells, a process that is dependent on STAT3 but not on ROR-gamma. IL-21 induces Th17 differentiation and suppresses FOXP3 expression, which requires STAT3 and ROR-gamma.
Applications Reported: Recombinant human IL-21 is biologically active. The intended use of the Recombinant Human IL-21 Single-Use ELISA RSG Standard is as a standard for human IL-21 Ready-SET-Go! ELISA and human IL-21 matched antibody pair ELISA. Typically the standard is run in a series of 7 doubling dilutions from the 'top' standard described below.
Instructions for use: For Ready-SET-Go! ELISA Set (TMB substrate). Dilution: Add 20 µL of standard solution to 5 mL of assay diluent to prepare the top standard solution (4000 pg/mL).
Note: These are single-use vials. Use one time and discard. Dilute as suggested above, not difficult-to-measure fractions of the suggested volumes (e.g., not 0.5 µL in 1.0 mL) or recovery may not be accurate. Use within 6 hours of dilution to top standard concentration.
Applications Tested: This cytokine standard has been calibrated, and subsequently tested by sandwich ELISA using the human IL-21 ELISA pair.
Source: A DNA sequence encoding the mature form of human IL-21 amino acids Gln25-Ser155 accession # NM_021803 was expressed in E.coli.
Purity: >98% as determined by SDS-PAGE.
Storage and handling: For best recovery, quick-spin vial prior to opening. For dilution of current stock, use ELISA Assay Diluent.
IL-21 is a 17 kDa immunomodulatory cytokine produced mainly by Natural Killer Cells (NKT), T helper (Th) 17 and T follicular helper (TFH) cells. In TFH cells, IL-21 expression leads to autocrine signaling through the IL-21 receptor (IL-21R) and STAT3, which leads to additional transcriptional activation by Bcl6. As with IFN gamma for Th1 and IL-4 for Th2 cells, IL-21 is critical for TFH cell development and effector function. IL-21 plays a role in T cell-dependent B cell differentiation into plasma cells and memory cells, stimulation of IgG production and induction of apoptotic signaling in naive B cells. In Th17 cells, IL-21 expression and autocrine feedback through STAT3, IRF4 and ROR gamma t lead to upregulation of the IL-23R, thereby preparing Th17 cells for maturation and maintenance by the inflammatory cytokine IL-23. While upregulating IRF4 and ROR gamma t, IL-21 also mediates the downregulation of Foxp3. IL-21 deficient mice are protected from developing colitis upon chemical treatment by their inability to upregulate Th17-associated molecules. In comparison, elevated levels of IL-21 are present in chemically-induced colitis mouse models.
For Research Use Only. Not for use in diagnostic procedures. Not for resale without express authorization.
Protein Aliases: CX2; il 21; IL-21; ILN; Interleukin; Interleukin-21; interleukin-21 isoform; Interleukin21; Za11
Gene Aliases: IL21
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