Recombinant Human ICOS-Fc Chimera (carrier-free)

Pricing & Availability
Other Names
Inducible costimulator, AILIM (activation inducible lymphocyte immunomediatory molecule) and CRP 1 (CD28 related protein 1), CD278, CVID1, H4
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Product Citations
Recombinant human ICOS-Fc Chimera is able to bind recombinant human B7-H2-Fc protein in a dose dependent manner. The Kd value of this binding is <5 nM.
  • ICOS_Human_Recombinant_BA_022714.jpg
    Recombinant human ICOS-Fc Chimera is able to bind recombinant human B7-H2-Fc protein in a dose dependent manner. The Kd value of this binding is <5 nM.
Cat # Size Price Quantity Avail. Save
599002 10 µg 64€
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599004 25 µg 100€
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599006 100 µg 236€
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Inducible costimulatory molecule (ICOS) is a member of CD28 superfamily protein. It has unique roles in T cell activation and differentiation, splenic germinal center formation, and immunoglobulin class switching. The expression of ICOS within the first 48 hours after T cell activation suggests that it may contribute to the differentiation of T cells during the primary response. ICOS binds to its ligand B7H, which is constitutively expressed at low levels on the surface of APCs and is upregulated by TNF-α or lipopolysaccharide. It was demonstrated that ICOS-B7H2 interaction plays an important role in the generation of CD4+ and CD8+ Tregs, and mediates the suppressive functions of CD4+ Tregs by regulating CTLA-4 expression on cell surfaces induced by allogeneic CD40-activated B cells. In the ICOS-KO mice, the T cell-mediated isotype switching is impaired while the IFN-gamma response is slightly affected; in addition, the ICOS-negative T cells do not accumulate in B cell follicles. Also, secondary, but not primary, clonal proliferation of antigen-specific B cells is impaired in ICOS-KO mice, and therefore the generation of secondary antibody-secreting cells is also impaired. These results suggest that this protein plays a pivotal role in T cell activation and Th1/Th2 differentiation.

Product Details
Technical data sheet

Product Details

Human ICOS, amino acids (Glu21-Phe141) (Accession# NP_036224.1), was expressed in CHO cells with a human IgG1 Fc tag at the C-terminus
Molecular Mass
The 359 amino acid recombinant protein with a C-terminal human IgG1 Fc tag has a predicted molecular mass of approximately 44 kD. The protein migrates above 60 kD in SDS-PAGE in DTT-reducing condition and above 120 kD in non-reducing condition. The N-terminal amino acid is Glu.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS
Endotoxin Level
Less than 0.1 EU per µg of protein as determine by the LAL method.
10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial (please contact technical support for concentration, or use our Lookup tool if you have a lot number.)
Please note, new lots of the 100 µg size will be lot-specific and may differ from previous lots that had a fixed concentration.
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.
Immobilized human ICOS-Fc Chimera at 1 µg/mL (100 µL/well) can bind recombinant human B7-H2-Fc in a dose dependent manner with a Kd < 5 nM.


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

Antigen Details


Activated T cells.

ICOS regulates the production of IL-4 and IL-10, immunoglobulin-isotype class switching, the formation of germinal centers, and regulation of T cell proliferation. ICOS expression is influenced by TCR and CD28 signals. CD28 costimulation enhances ICOS expression, and ICOS upregulation is markedly reduced in the absence of B7-1 and B7-2.
Antigen presenting cells, B cells.
B7-H2 (ISCOL, CD275).
Human ICOS is able to bind hB7-H2.
Cell Type
B cells, Dendritic cells, Tregs
Biology Area
Cell Adhesion, Cell Biology, Immunology, Signal Transduction, Costimulatory Molecules
Molecular Family
Immune Checkpoint Receptors, Soluble Receptors, TCRs
Antigen References

1. Arimura Y, et al. 2002. Int. Immunol. 14:555.
2. Mahajan S, et al. 2007. Eur. J. Immunol. 37:1796.
3. Harada H, et al. 2003. J. Clin. Invest. 112:234.
4. Dong C, et al. 2001. Nature. 409:97.
5. McAdam AJ, et al. 2001. Nature. 409:102.

Gene ID
28951 View all products for this Gene ID
View information about ICOS on

Related FAQs

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.

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.

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)
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.

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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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