CD28 (Cluster of Differentiation 28) is one of the proteins expressed on T cells that provide co- stimulatory signals required for T cell activation and survival. T cell stimulation through CD28 in addition to the T-cell receptor (TCR) can provide a potent signal for the production of various interleukins (IL-6 in particular). The CD28 gene is mapped to 2q33-q34. 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. Sample Type: Cell lysates, cell culture supernates, serum, plasma (heparin or EDTA). Intended Use: Sandwich High Sensitivity BioAssay(TM) ELISA kit for Quantitative Detection of Human CD28. Sensitivity: <12pg/ml Range: 62.5pg/ml-4000pg/ml Specificity: Recognizes natural and recombinant Human CD28. There is no detectable cross-reactivity with other relevant proteins. Test Principle: This Human CD28 BioAssay(TM) ELISA Kit was based on standard sandwich enzyme-linked immune-sorbent assay technology. A specific for CD28 has been precoated onto 96-well plates. Standards(Expression system for standard: NSO, Immunogen sequence: N19-P152) and test samples are added to the wells, a biotinylated detection specific for CD28 is added subsequently and then followed by washing with PBS or TBS buffer. Avidin-Biotin-Peroxidase Complex was added and unbound conjugates were washed away with PBS or TBS buffer. HRP substrate TMB was used to visualize HRP enzymatic reaction. TMB was catalyzed by HRP to produce a blue color product that changed into yellow after adding acidic stop solution. The density of yellow is proportional to the Human CD28 amount of sample captured in plate. Kit Components: 96-well plate precoated with anti-Human CD28 antibody, 1x plate Lyophilized recombinant Human CD28 standard, 2x10ng/tube Biotinylated anti-Human CD28 antibody, 1x130ul (dilution 1:100) Avidin-Biotin-Peroxidase Complex (ABC), 1x130ul (dilution 1:100) Sample diluent buffer, 1x30ml Antibody diluent buffer, 1x12ml ABC diluent buffer, 1x12ml TMB color developing agent, 1x10ml TMB stop solution, 1x10ml PBS washing buffer Powder for 1000ml, 1x buffer Storage and Stability: Store powder at 4C liquid at -20C. Store other components at 4C. Stable for at least 6 months For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
