• Species Reactivity

  Human

• Specificity

  Detects human CD28 in Western blots. In Western blots, this antibody does not cross-react with recombinant mouse (rm) CD28, rhCTLA4, or rmCTLA4.

• Source

  Monoclonal Mouse IgG    ₁ Clone # 37407

• Purification

  Protein A or G purified from ascites

• Immunogen

  S. frugiperda insect ovarian cell line     Sf 21-derived recombinant human CD28    
  Asn19-Pro152    
  Accession # P10747

• Formulation

  Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied as a 0.2 µm filtered solution in PBS.

• Endotoxin Level

  <0.10 EU per 1 μg of the antibody by the LAL method.  

• Label

  Unconjugated

Applications

• Recommended    
  Concentration

  Sample

• Western Blot

  1 µg/mL

  Recombinant Human CD28 Fc Chimera (Catalog # )    
  under non-reducing conditions only

• 
  

• Agonist Activity

  0.2-0.6 µg/mL

  See below

• 
  

Please Note: Optimal dilutions should be determined by each laboratory for each application.  are available in the Technical Information section on our website.

Data Examples

Preparation and Storage

• Reconstitution

  Reconstitute at 0.5 mg/mL in sterile PBS.

• Shipping

  The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C

• Stability & Storage

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

• 12 months from date of receipt, -20 to -70 °C as supplied.

• 1 month, 2 to 8 °C under sterile conditions after reconstitution.

• 6 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: CD28

CD28 and CTLA-4, together with their ligands, B7-1 and B7-2, constitute one of the dominant costimulatory pathways that regulate T and B cell responses. CD28 and CTLA-4 are structurally homologous molecules that are members of the immunoglobulin (Ig) gene superfamily. Both CD28 and CTLA-4 are composed of a single Ig
V‑like extracellular domain, a transmembrane domain and an intracellular domain. CD28 and CTLA-4 are both expressed on the cell surface as disulfide-linked homodimers or as monomers. The genes encoding these two molecules are closely linked on human chromosome 2 and mouse chromosome 1. Mouse CD28 is expressed constitutively on virtually 100% of mouse T cells and on developing thymocytes. Cell surface expression of mouse CD28 is down-regulated upon ligation of CD28 in the presence of PMA or PHA. In contrast, CTLA-4 is not expressed constitutively but is up-regulated rapidly following T cell activation and CD28 ligation. Cell surface expression of mouse CTLA-4 peaks approximately 48 hours after activation. Although both CTLA-4 and CD28 can bind to the same ligands, CTLA-4 binds to B7-1 and B7-2 with a 20-100 fold higher affinity than CD28. CD28/B7 interaction has been shown to prevent apoptosis of activated T cells via the upregulation of Bcl-x_L. CD28 ligation has also been shown to regulate Th1/Th2 differentiation.

• References:

1. Lenschow, D.J. et al. (1996) Annu. Rev. Immunol. 14:233.

2. Hathcock, K.S. and R.J. Hodes (1996) Advances in Immunol. 62:131.

3. Ward, S.G. (1996) Biochem. J. 318:361.

• Entrez Gene IDs:

  940 (Human); 12487 (Mouse); 102146670 (Cynomolgus Monkey)

• Alternate Names:

  CD28 antigen (Tp44); CD28 antigen; CD28 molecule; CD28; MGC138290; T-cell-specific surface glycoprotein CD28; Tp44