Human CTLA-4 enzyme-linked immunoassay kit
| Specification | 96 Test |
|---|---|
| Sensitivity | 1.33 pg/ml (50 μl)；1.97 pg/ml (10 μl)； |
| Standard Curve Range | 2.74~2000 pg/ml |
| Standard Curve Gradient | 7 Points/3 Folds |
| Number of Incubations | 2 |
| Detectable sample | Liquid phase sample of soluble substances. For example: serum, plasma, cell culture supernatant, tissue grinding liquid, etc. |
| Sample Volume | 50 μl/10 μl |
| Type | Fully Ready-to-Use |
| Operation Duration | 120min |
| pg/ml | O.D. | Average | Corrected | |
|---|---|---|---|---|
| 0.00 | 0.0105 | 0.0103 | 0.0104 | |
| 2.74 | 0.0171 | 0.0159 | 0.0165 | 0.0061 |
| 8.23 | 0.0282 | 0.0271 | 0.0277 | 0.0173 |
| 24.69 | 0.0616 | 0.0611 | 0.0614 | 0.0510 |
| 74.07 | 0.1683 | 0.1480 | 0.1582 | 0.1478 |
| 222.22 | 0.5143 | 0.4790 | 0.4967 | 0.4863 |
| 666.67 | 1.5540 | 1.5790 | 1.5665 | 1.5561 |
| 2000.00 | 3.9590 | 3.9100 | 3.9345 | 3.9241 |
Precision
| Intra-assay Precision | Inter-assay Precision | |||||
| Sample Number | S1 | S2 | S3 | S1 | S2 | S3 |
| 22 | 22 | 22 | 6 | 6 | 6 | |
| Average(pg/ml) | 53.1 | 266.2 | 814.9 | 17.2 | 77.5 | 231.4 |
| Standard Deviation | 2.9 | 9.1 | 34.8 | 1.3 | 5.1 | 12.0 |
| Coefficient of Variation(%) | 5.5 | 3.4 | 4.3 | 7.8 | 6.6 | 5.2 |
Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested twenty times on one plate to assess intra-assay precision.
Inter-assay Precision (Precision between assays) Three samples of known concentration were tested six times on one plate to assess intra-assay precision.
Spike Recovery
The spike recovery was evaluated by spiking 3 levels of human CTLA-4 into health human serum sample. The un-spiked serum was used as blank in this experiment.
The recovery ranged from 91% to 97% with an overall mean recovery of 94%.
Sample Values
| Sample Matrix | Sample Evaluated | Range (pg/ml) | Detectable (%) | Mean of Detectable (pg/ml) |
|---|---|---|---|---|
| Serum | 30 | 0.31-3.78 | 100 | 1.11 |
Serum/Plasma – Thirty samples from apparently healthy volunteers were evaluated for the presence of CTLA-4 in this assay. No medical histories were available for the donors.
Product Data Sheet
Background: CTLA-4
CTLA-4 (cytotoxic T-lymphocyte-4, designated CD152), is a type I transmembrane T cell inhibitory molecule that is a member of the Ig superfamily. Human or mouse CTLA-4 cDNA encodes 223 amino acids (aa) including 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 is found as a covalent homodimer of 41‑43 kDa. Within the ECD, human CTLA-4 shares 68%, 71% and 83‑86% aa sequence identity with mouse, rat and porcine/bovine/rabbit/feline/canine CTLA-4, respectively. A 174 aa form that lacks TM and cytoplasmic sequences (sCTLA-4) is possibly secreted. Isoforms of 56‑79 aa that mainly contain parts of the cytoplasmic domain are reported. In mouse, an isoform lacking the Ig-like domain has ligand-independent inhibitory activity and is termed liCTLA-4. CD28, which is structurally related to CTLA-4, is constitutively expressed on naïve T cells and promotes T cell activation when engaged by B7-2 on antigen-presenting cells (APC) within the immunological synapse (IS). In contrast, CTLA-4 is recruited from intracellular vesicles to the IS beginning 1, 2 days after T cell activation. It forms a linear lattice with B7‑1 on APC, inducing negative regulatory signals and ending T cell activation. Abatacept, a therapeutic human CTLA-4-Ig fusion protein (trade name Orencia), competes with CD28 for B7-1 and B7-2 binding and has been used to antagonize T cell activation in autoimmune conditions and to enhance transplant survival. Mice deleted for CTLA-4 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, which constitutively express CTLA-4 in wild-type mice and humans.
