More info
Assay Range | 156 - 10,000 pg/mL |
Sensitivity | 10.0 pg/mL |
Size | 96T |
Storage | Store at 2 - 8ºC. Keep reconstituted standard and detection Ab at -20 ºC |
Assay Principle | Sandwich ELISA |
Sample volume | 100 µL final volume, dilution factor varies on samples. |
Detection Method | Chromogenic |
Kit Components
1. Recombinant Mouse CTLA-4 standard: 2 vials.
2. One 96-well plate precoated with anti- Mouse CTLA-4 Ab
3. Sample diluent buffer: 12 mL - 1
4. Detection antibody: 130 µL, dilution 1:100.
5. Streptavidin-HRP: 130 µL, dilution 1:100
6. Antibody diluent buffer: 12 mL x1
7. Streptavidin-HRP diluent buffer: 12 mL x1
8. TMB developing agent: 10 mL x1
9. Stop solution: 10 mL x1.
10. Washing solution (20x): 25 mL x1.
Background
CTLA-4 (cytotoxic T-lymphocyte-associated protein 4), also known as CD152, is a protein receptor belonging to the immunoglobulin superfamily, which is expressed on the surface of helper T cells. Human or mouse CTLA-4 is synthesized as a 223 amino acid (aa) precursor containing a 35 aa signal sequence, a 126 aa extracellular domain (ECD) with one Ig-like V-type domain, a 21 aa transmembrane (TM) sequence, and a 41 aa cytoplasmic sequence. It exists as a covalent homodimer. The ECD of mouse CTLA-4 shares 94% and approximately 70% aa sequence identity with rat and human CTLA-4, respectively. In mouse, an isoform lacking the Ig-like domain has ligand-independent inhibitory activity and is termed liCTLA-4. CTLA-4 is structurally homologous to CD28, both of them consist of a single Ig V-like extracellular domain, a transmembrane domain and an intracellular domain. Alternatively spliced variants including membrane-bound isoform and soluble isoform (sCTLA-4) have been characterized. CTLA-4 and CD28 play a critical role in regulating co-stimulatory effects in immune system by binding to their ligands, CD80 (B7-1) and CD86 (B7-2), respectively. CTLA-4 transduces an inhibitory signal to T cells, whereas CD28 transduces a stimulatory signal. The mechanisms by which CTLA-4 inhibits T cell responses are currently uncertain. It may act by SHP-2 and PP2A dephosphorylation of TCR-proximal signaling proteins such as CD3 and LAT, it can also compete with CD28 for CD80/86 binding to affect the downstream signaling pathways. CTLA-4 knock-out mice show no abnormalities until after birth, but then develop lethal autoimmune reactions due to continued T cell activation and poor control by regulatory T cells.
Clinically, high levels of sCTLA-4 have been found in some patients with autoimmune thyroid disease (ATD). Polymorphisms of CTLA-4 gene have been correlated to autoimmune thyroid disease and multiple sclerosis. Mutations in CTLA-4 gene have been identified in insulin-dependent diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, celiac disease, systemic lupus erythematosus, thyroid-associated orbitopathy.