Retinol Binding Protein 4 (RBP4) Rapid Human ELISA Kit

Retinol binding protein 4(RBP4), originally known as a specific transport of retinol in blood, is also a novel inflammatory and insulin resistance marker. Serum RBP4 levels are elevated in insulin-resistant mice and humans with obesity and type 2 diabetes. Animal experiments found that increased secretion of RBP4 might reduces insulin-dependent glucose uptake by muscle tissue by reducing the activity of PI(3)K (phosphoinositide 3-kinase), and increased hepatic glucose output by increasing the expression of the enzyme PEPCK2. Studies suggested that elevated serum RBP4 was associated with components of the metabolic syndrome, including increased body-mass index, waist-to-hip ratio, serum triglyceride levels, and systolic blood pressure and decreased high-density lipoprotein cholesterol levels4. Furthermore, circulating RBP4 concentrations were associated with subclinical cardiovascular disease, which imply that RBP4 could be involved in the development of atherosclerosis.

This assay utilises a quantitative sandwich Enzyme-Linked Immunosorbent Assay (ELISA) technique and is designed for the quantitative detection of human RBP4 in plasma or serum in 2.5 hours. A mouse monoclonal antibody specific to RBP4 has been pre-coated onto a micro-titre plate. The user pipettes standards and samples into the wells and any RBP4 present is captured by the immobilised antibody. After washing away any unbound substances a second horseradish peroxidase (HRP)-linked antibody specific to RBP4 is added to the wells. After a final wash step to remove any unbound antibody-enzyme reagent, an HRP substrate solution is added and colour develops in proportion to the amount of RBP4 bound initially. The assay is stopped and the optical density of the wells determined using a microplate reader. Since the increases in absorbance are directly proportional to the amount of captured RBP4, the unknown sample concentration can be interpolated from a reference curve included in each assay.

This Human RBP4 ELISA kit is designed for quantification of human RBP4 in serum, plasma and adipocyte extracts or cell culture media. Other biological matrices have not been tested. This kit specifically measures native human RBP4 and has no cross reactivity to mouse or rat RBP4.