Human IL-21 Recombinant Protein

Product Specific Information

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 has been reported for use in cytokine bioassays, and ELISA. For research use only, not for diagnostic or therapeutic use. The recombinant human IL-21 has been reported useful for bioassay and ELISA.

Applications Tested: The ED50 of this protein, as measured by B9 cell proliferation assay, is less than or equal to 25 ng/mL. This corresponds to a specific activity of greater than or equal to 4 x 10e4 Units/mg.

Source: A DNA sequence encoding the mature form of human IL-21 amino acids Gln25-Ser155 accession # NM_021803 was expressed in E.coli.

Bioactivity: The ED50 of this protein, as measured by B9 cell proliferation assay, is less than or equal to 25 ng/mL. This corresponds to a specific activity of greater than or equal to 4 x 10e4 Units/mg.

Endotoxin: Less than 0.01 ng/ug cytokine as determined by the LAL assay. Purity: >98% as determined by SDS-PAGE.

Molecular Weight: The protein has a predicted molecular mass of 17,150. The DTT reduced protein migrates as a 18 kDa polypeptide on SDS-PAGE. The non-reduced protein migrates as a 17 kDa polypeptide.

Storage and handling: For best recovery, quick-spin vial prior to opening. Use in a sterile environment.

Purity: Greater than 90%, as determined by SDS-PAGE.

Aggregation: Less than 10%, as determined by HPLC.

Filtration: 0.2 µm post-manufacturing filtered.

Target Information

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.