Recombinant Human CD28-Fc Chimera (carrier-free)

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Regulatory Status
Other Names
T-cell-specific surface glycoprotein CD28
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Immobilized CD28 binds human B7.1 (1µg/mL) with an ED50 of 0.4 - 2.0 µg/mL.
  • CD28-FcChimera_Human_RECOM_BA_022316
    Immobilized CD28 binds human B7.1 (1µg/mL) with an ED50 of 0.4 - 2.0 µg/mL.
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755706 100 µg £174
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CD28 was initially identified by antibodies as a 44 kD protein on the membrane of human T cells. CD28 is a 23 kD glycosylated type 1 transmembrane protein, which forms a disulfide-linked homodimer. CD28 is a costimulatory receptor that synergizes with TCR-mediated signals to enhance cytokine production and the proliferation of T cells. CD28 plays a primordial role for the priming of naive T cells. CD28, cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, CD152), inducible costimulatory (ICOS), programmed death receptor 1 (PD-1), and B- and T- lymphocyte attenuator (BTLA) are members of the family of costimulatory receptors. CD28 and CTLA-4 both bind the same ligands B7-1 (CD80) and B7-2 (CD86). CD28 and ICOS mainly induce T-cell activation while as CTLA-4, PD-1, and BTLA are inhibitory. In murine plasmacytoid dendritic cells, CD28 signaling induces the downregulation of type I interferon production, which contrasts with its activation role in T cells. CD28 is also expressed on normal murine and human plasma cells (PCs). It promotes PC survival, sustained antibody responses, and the upregulation of transcriptional repressor B lymphocyte-induced maturation protein-1 (Blimp-1), which is a master regulator of PC differentiation. CD28 is also expressed in malignant BM-resident PC of multiple myeloma (MM) and its overexpression in myeloma cells is associated to bad prognostics. The soluble costimulatory molecule CD28 has been detected in the serum of patients with systemic lupus erythematosus, primary Sjögren's syndrome, and systemic sclerosis. Soluble CD28 results from the shedding of the membrane-bound form.

Product Details
Technical Data Sheet (pdf)

Product Details

Human CD28, amino acids (Asn19-Pro152) (Accession# NM_006139), was expressed in 293E cells with a C-terminal human IgG Fc.
Molecular Mass
The 368 amino acid recombinant protein has a predicted molecular mass of approximately 41.5 kD. The DTT-reduced and non-reduced protein migrates at approximately 60 kD and 120 kD respectively by SDS-PAGE. The predicted N-terminal amino acid is Asn.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS, pH 6.0.
Endotoxin Level
Less than 0.1 EU per µg of protein as determined 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. To obtain lot-specific concentration and expiration, please enter the lot number in our Certificate of Analysis online tool.
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 CD28 binds human B7.1 (1 µg/mL) with an ED50 of 0.4 - 2.0 µg/mL.


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


CD4, CD8 lymphocytes, immature CD3-, CD8+, CD4+ CD8+ cells, on CD4- CD8- cells, and normal plasma cells.

Activation of naïve T cells, induction of cytokine production, cell survival, and expression of anti-apoptotic proteins including Bcl-XL.
Antigen presenting cells.
B7-1 (CD80) and B7-2 (CD86).
Biology Area
Immunology, Costimulatory Molecules
Molecular Family
CD Molecules, Immune Checkpoint Receptors, Soluble Receptors
Antigen References

1. Hansen JA, et al. 1980. Immunogenetics 5:429-39.
2. Gross JA, et al. 1992. J. Immunol. 149:380.
3. Coyle AJ, Gutierrez-Ramos JC. 2001. Nat. Immunol. 2:203.
4. Hebbar M, et al. 2004. Clin. Exp. Immunol. 136:388.
5. Boomer JS, Green JM. 2010. Cold Spring Harb. Perspect Biol. 8:a002436.
6. Rozanski CH, et al. 2011. J. Exp. Med. 208:1435.
7. Rozanski CH, et al. 2015. J. Immunol. 194:4717.

Gene ID
940 View all products for this Gene ID
View information about CD28 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) = 10^6/ ED50 (ng/mL)

Go To Top Version: 1    Revision Date: 02/24/2016

For Research Use Only. Not for diagnostic or therapeutic use.


This product is supplied subject to the terms and conditions, including the limited license, located at ("Terms") and may be used only as provided in the Terms. Without limiting the foregoing, BioLegend products may not be used for any Commercial Purpose as defined in the Terms, resold in any form, used in manufacturing, or reverse engineered, sequenced, or otherwise studied or used to learn its design or composition without express written approval of BioLegend. Regardless of the information given in this document, user is solely responsible for determining any license requirements necessary for user’s intended use and assumes all risk and liability arising from use of the product. BioLegend is not responsible for patent infringement or any other risks or liabilities whatsoever resulting from the use of its products.


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