CD28 is a single-pass type I transmembrane glycoprotein that belongs to the CD28/CTLA4 (cytotoxic T lymphocyte-associated antigen 4, also known as CD152) family of the immunoglobulin (Ig) superfamily. CD28 and CTLA-4 are structurally homologous molecules and both contain one Ig-like V-type domain in the extracellular region. CD28 and CTLA4 are expressed on the cell surface as disulfide­linked homodimers or as monomers. Together with their ligands, CD80 and CD86, they constitute one of the dominant co-stimulatory pathways that regulate T and B cell responses. CD28 is expressed in T-cells and plasma cells, but not in less mature B-cells. CD28 is involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.  CD28 is expressed constitutively on nearly all mouse T cells and surface expression is down­regulated upon ligation of CD28. CTLA­4 is not constitutively expressed but is up­regulated rapidly following T cell activation and CD28 ligation. The binding of CD80 and CD86 to its receptor CD28 induces T-cell proliferation and cytokine production. CD28 ligation has also been shown to regulate Th1/Th2 differentiation. CTLA4 binds to CD80 and CD86 with a 20-100 fold higher affinity than CD28 and is involved in the downregulation of the immune response. The CD80/CD86/CD28/CTLA4 pathway can positively and negatively regulate immune responses. CD28 is thus regarded as a promising therapeutic target for autoimmune diseases and cancer.

CD28 is a single-pass type I transmembrane glycoprotein that belongs to the CD28/CTLA4 (cytotoxic T lymphocyte-associated antigen 4, also known as CD152) family of the immunoglobulin (Ig) superfamily. CD28 and CTLA-4 are structurally homologous molecules and both contain one Ig-like V-type domain in the extracellular region. CD28 and CTLA4 are expressed on the cell surface as disulfide­linked homodimers or as monomers. Together with their ligands, CD80 and CD86, they constitute one of the dominant co-stimulatory pathways that regulate T and B cell responses. CD28 is expressed in T-cells and plasma cells, but not in less mature B-cells. CD28 is involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.  CD28 is expressed constitutively on nearly all mouse T cells and surface expression is down­regulated upon ligation of CD28. CTLA­4 is not constitutively expressed but is up­regulated rapidly following T cell activation and CD28 ligation. The binding of CD80 and CD86 to its receptor CD28 induces T-cell proliferation and cytokine production. CD28 ligation has also been shown to regulate Th1/Th2 differentiation. CTLA4 binds to CD80 and CD86 with a 20-100 fold higher affinity than CD28 and is involved in the downregulation of the immune response. The CD80/CD86/CD28/CTLA4 pathway can positively and negatively regulate immune responses. CD28 is thus regarded as a promising therapeutic target for autoimmune diseases and cancer.

 

Product Details

 

Gene Symbol: CD28; TP44; TP-44

 

NCBI Gene ID: 940

 

Uniprot Entry: P10747

 

Construct Details: Expressed as the combination of a heavy chain (HC) containing VH from anti-CD28 mAb and CH1-3 region of human IgG1 and a light chain (LC) encoding VL from anti-CD28 mAb and CL of human kappa light chain.  Exists as a disulfide linked dimer of the HC and LC hetero-dimer under non-reducing condition.

 

Source: Mammalian cells stably expressing anti-CD28 heavy chain and light chain (in human IgG1,k format) and growing in chemical-defined media with no animal components. 

 

M.W.: Calculated molecular mass (kDa): 147 (49 kDa for a single HC, 24.5 kDa for a single LC); Estimated by SDS-PAGE under non-reducing condition(kDa): 150

 

Purity: >95% judged by SDS-PAGE under reducing condition (see the gel image above, labeled as DTT "+")

 

Formulation: Supplied at 1.0 mg/ml in sterile PBS pH7.4 without any carrier protein or preservative (the concentration determined by UV absorption with an A280nm of 1.0 for 0.73 mg/ml of IgG and verified by SDS-PAGE and Coomassie blue staining)

 

Endotoxin Level: <0.1 EU per 1 μg of purified recombinant protein determined by the LAL method

 

Biological Activity: Binds human CD28-Fc protein (SKU#: FCL0729) with high affinity (apparent K_D < 1 nM - see the Technical Data) by a functional ELISA. Recognizes cell surface human CD28 by flow cytometry, IHC staining and fluorescent microscopy. Mimics the ligand-­binding to activate CD28 signaling and enhances T cell-mediated anti-tumor immunity in vivo. 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.

 

Technical Data

 

Recombinant CD28-Fc protein (SKU#FCL0729) was immobilized at 100 ng/well on a 96-well NuncMaxisorp plate for ELISA with serially diluted biotinylated anti-human CD28 monoclonal antibody, human IgG1 (SKU#MAB1827). Biotinyalted anti-CD137 (SKU#MAB1829) human IgG1 was used as a negative control to demonstrate the specificity of CD28 binding under the experimental conditions.  The binding curve was fit and apparent K_D was calculated for anti-CD28: CD28 binding to be 32 ± 3 pM.   

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

 

 

Storage

 

The product is shipped at 4°C. Upon receipt, centrifuge the product briefly before opening the vial. It is recommended to store small aliquots at the temperature below –20°C for long-term storage and the product is stable for at least 3 months. The undiluted protein can be stored at 4°C for no more than 2 weeks.

 

 

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

 

References

 

1. Annu Rev Immunol. 11 :191-212 (1993).

2. Advances in Immunol. 62:131 (1996). 

3. Biochem. J. 318:361 (1996). 

4. Blood 99:2138-2145(2002) 

5. Nat. Immunol. 6:271-279(2005)

 

 

 

Documentation

 

Product datasheet (pdf) can be downloaded here: MAB1827-PDS.pdf

 

 

 

Additional supporting documents, including COA and MSDS are available upon request.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.