Enzyme-linked Immunosorbent Assay (ELISA), also known as an Enzyme Immunoassay (EIA), is an immunological technique used to detect the presence of an antibody or an antigen in a sample. ELISA combines the specificity of antibodies with the sensitivity of simple enzyme assays, by using antibodies or antigens coupled to an easily assayed enzyme that possesses a high turnover number. The assay generally requires the use of a measureable detection medium, including colorimetric, chemiluminescent or fluorescent systems. Unlike Western blots, which use precipitating substrates, ELISA procedures utilize substrates that produce soluble products. Ideally the enzyme substrates should be stable, safe and inexpensive. In a properly optimized assay, the intensity of the signal generated is directly proportional to the amount of reactant present. In an ELISA, an antigen must be immobilized to a solid surface and then complexed with an antibody that is linked to an enzyme. Detection is accomplished by assessing the conjugated enzyme activity via incubation with a substrate to produce a measureable product. Generally there are five types of ELISA they are: Direct ELISA, Indirect ELISA, Sandwich ELISA, Competitive ELISA, Multiplex ELISA.
The direct ELISA Kit uses the method of directly labeling the antibody itself where as indirect; two-step method uses a labeled secondary antibody for detection. In case of sandwich ELISA Kit, it measures the amount of antigen between two layers of antibodies. The antigens to be measured must contain at least two antigenic sites capable of binding to the antibody, since at least two antibodies act in the sandwich. But in competitive ELISA Kit, the enzyme may be linked to either the antigen or the primary antibody. In this type of Kit, there is an inverse relationship between the signal obtained and the concentration of the analyte in the sample, due to the competition between the free analyte and the ligand-enzyme conjugate for the antibody coating the microplate, i.e. the more analyte the lower the signal. Whereas multiplex ELISA Kit is widely used microtiter plate towards a protein array format that allows simultaneous detection of multiple analytes at multiple arrays addresses within a single well. Recent studies revealed that ELISA Kit is a useful tool for determining serum antibody concentrations (such as with the HIV test or West Nile Virus). It has also found applications in the food industry in detecting potential food allergens such as milk, peanuts, walnuts, almonds, and eggs. ELISA can also be used in toxicology as a rapid presumptive screen for certain classes of drugs.
ACTIVE ELISA Kits are generally available for the analysis of specific cytokines like Interleukin proteins, chemokines, and signaling targets in serum, plasma and culture supernatant samples from human, mouse and other species. IMGENEX ELISA kits help provide accurate and consistent results. Kits are developed and validated for sensitivity, specificity, dynamic range, and consistency ensuring high quality. We are continually developing new ELISA kits to meet future research needs, with a focus on Interleukins.
Interleukin proteins are a subset of a larger group of cellular messenger molecules called cytokines, which are modulators of cellular behaviour. Like other cytokines, Interleukin proteins are not stored within cells but are instead secreted rapidly, and briefly, in response to a stimulus, such as an infectious agent. Once an Interleukin has been produced, it travels to its target cell and binds to it via a receptor molecule on the cell’s surface. This interaction triggers a cascade of signals within the target cell that ultimately alter the cell’s behaviour. The function of the immune system depends in a large part on Interleukin proteins. The majority of Interleukin proteins are synthesized by helper CD4+ T lymphocytes, as well as through monocytes, macrophages, and endothelial cells. They promote the development and differentiation of T, B, and hematopoietic cells. Thirty-five different types of Interleukin proteins (IL-1~IL-35) and two main families of receptors (type 1 and type 2) are known. IMGENEX’s ELISA Kit provides complete analysis of major Interleukin proteins. For details regarding specific ELISA Kit, click on the individual links.