Recombinant Mouse IL-21 (carrier-free)

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Product Citations
CTLL-2 cell proliferation induced by mouse IL-21.
  • IL-21_Mouse_110311
    CTLL-2 cell proliferation induced by mouse IL-21.
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574502 10 µg 175€
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574504 25 µg 329€
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574506 100 µg 825€
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574508 500 µg 2620€
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IL-21 was identified by a functional screening from conditioned medium of activated T cells using Baf3-IL-21R transfectans. In normal B cells, IL-21 can mediate cell proliferation, growth arrest, and terminal differentiation, or apoptosis, depending on their activation status. IL-21 enhances B cell proliferation following incubation with an activating CD40 antibody. This result suggests that IL-21 enhances B cell function following T:B cell interactions. Nevertheless, IL-21 inhibits the proliferation of murine and human B cells stimulated with anti-IgM antibodies. In addition, IL-21 enhaces proliferation, cytotoxic activity, and IFNγ production by CD8-effector T cells, and induces terminal differentiation of activated natural killer (NK) cells. Also, IL-21 can drive Th17 responses in conjunction with TGFβ. Nevertheless, IL-21 is not essential for the differentiation of Th17 cells in vitro and in vivo, as it was showed using IL-21 and IL-21R-deficient mice. IL-6 induces the production of IL-21 from CD4 T cells upon TCR stimulation, and IL-6 and IL-21 are key players in the Tfh differentiation, characterized by increased protein expression of both Bcl6 and CXCR5. IL-21R complex is formed with the IL-21R-alpha chain and the common subunits (γc) shared with other interleukins such as IL-2, IL-4, IL-7, IL-9, and IL-15. IL-21R is wildly expressed on T cells, B cells, NK cells, and dendritic cells in all lymphoid tissues, as well as some nonimmune cells, such as fibroblasts and epithelial cells.

Product Details
Technical data sheet

Product Details

Mouse IL-21, amino acids Pro25-Ser146 (Accession# NP_068554) was expressed in E. coli.
Molecular Mass
The 122 amino acid recombinant protein has a predicted molecular mass of approximately 14.2 kD. The DTT-reduced and non-reduced proteins migrate at approximately 20 kD by SDS-PAGE. The N-terminal amino acid is Pro.
>98%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS.
Endotoxin Level
Less than 0.01 ng per µg cytokine as determined by the LAL method.
10 and 25 µg sizes are bottled at 100 µg/mL. 100 µg and larger sizes are lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration, please enter the lot number in our Concentration and Expiration Lookup or Certificate of Analysis online tools.
Storage & Handling
Unopened vial can be stored between 2°C and 8°C for up to 2 weeks, at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
Bioactivity was measured by its property to stimulate the proliferation of CTLL-2 cells in a dose dependent manner. ED50 = 15 - 60 ng/ml, corresponding to a specific activity of 1.7 - 6.7 x 104 units/mg.


Application Notes

BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at

Product Citations
  1. Wang Y, et al. 2016. Sci Rep. 6:31881. PubMed

Antigen Details


CD4 activated T cells, Th17 cells, NK T cells.

IL-21 induces T and B cell proliferation, B cell Ig class switching to IgG production, decreases DC function, enhances differentiation of effector and central memory T cells, and regulates T cell and hematopoietic progenitor cell homeostasis.
T cells, B cells, NK cells, NKT cells, dendritic cells, fibroblast, epithelial cells.
IL-21R and the common γc subunit (CD132) are components of the IL-21R complex.
Cell Type
Hematopoietic stem and progenitors
Biology Area
Immunology, Innate Immunity, Stem Cells, Cell Biology
Molecular Family
Antigen References

1. Parrish-Novak J, et al. 2000. Nature 408:57.
2. De Totero D, et al. 2006. Blood 107:3708.
3. Korn T, et al. 2007. Nature 448:484
4. Coquet JM, et al. 2008. J. Immunol. 180:7097.
5. Rincon M, et al. 2008. J. Exp. Med. 2.06:69.
6. Kaplan MH, et al. 2011. Blood 117:6198.
7. Eto D, et al. 2011. PLOS One 6(3):e17739.

Gene ID
60505 View all products for this Gene ID
View information about IL-21 on

Related FAQs

Why choose BioLegend recombinant proteins?

     • Each lot of product is quality-tested for bioactivity as indicated on the data sheet.
     • Greater than 95% Purity or higher, tested on every lot of product.
     • 100% Satisfaction Guarantee for quality performance, stability, and consistency.
     • Ready-to-use liquid format saves time and reduces challenges associated with reconstitution.
     • Bulk and customization available. Contact us.
     • Learn more about our Recombinant Proteins.

How does the activity of your recombinant proteins compare to competitors?

We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!

What is the specific activity or ED50 of my recombinant protein?

The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.

Have your recombinants been tested for stability?

Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.

Does specific activity of a recombinant protein vary between lots?

Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.

How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
Use formula Specific activity (Units/mg) = 10e6/ ED50 (ng/mL)
Go To Top Version: 3    Revision Date: 10.10.2016

For research use only. Not for diagnostic use. Not for resale. BioLegend will not be held responsible for patent infringement or other violations that may occur with the use of our products.


*These products may be covered by one or more Limited Use Label Licenses (see the BioLegend Catalog or our website, BioLegend products may not be transferred to third parties, resold, modified for resale, or used to manufacture commercial products, reverse engineer functionally similar materials, or to provide a service to third parties without written approval of BioLegend. By use of these products you accept the terms and conditions of all applicable Limited Use Label Licenses. Unless otherwise indicated, these products are for research use only and are not intended for human or animal diagnostic, therapeutic or commercial use.


BioLegend Inc., 8999 BioLegend Way, San Diego, CA 92121
Toll-Free Phone: 1-877-Bio-Legend (246-5343) Phone: (858) 768-5800 Fax: (877) 455-9587


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