Description
Principle of the assay: This assay employs a two-site sandwich ELISA to quantitative IL-18 in Human serum, plasma, saliva, urine. An antibody specific for IL-18 has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any IL-18 present is bound by the immobilized antibody. After removing any unbound substances, a biotin - conjugated antibody specific for IL-18 is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of IL-18 bound in the initial step. The color development is stopped and the intensity of the color is measured.
Background: Interleukin-18 (IL18, also known as interferon-gamma inducing factor) is a protein which in humans is encoded by the IL18 gene. The protein encoded by this gene is a proinflammatory cytokine. IL-18 is a cytokine that belongs to the IL-1 superfamily and is produced by macrophages and other cells. IL-18 works by binding to the interleukin-18 receptor, and together with IL-12 it induces cell-mediated immunity following infection with microbial products like lipopolysaccharide (LPS). After stimulation with IL-18, natural killer (NK) cells and certain T cells release another important cytokine called interferon-gamma (IFN-gamma) or type II interferon that plays an important role in activating the macrophages or other cells. The combination of this cytokine and IL12 has been shown to inhibit IL-4 dependent IgE and IgG1 production, and enhance IgG2a production in B cells. IL-18 binding protein (IL18BP) can specifically interact with this cytokine, and thus negatively regulate its biological activity