Description
Introduction: Interleukin-18 (IL-18), a recently described member of the IL-1 cytokine superfamily, is now recognized as an important regulator of innate and acquired immune responses. IL-18 is expressed at sites of chronic inflammation, in autoimmune diseases, in a variety of cancers, and in the context of numerous infectious diseases. IL-18 works together with IL-12 to induce cell-mediated immunity followipg 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 activatipg the macrophages or other cells. Apart from its physiological role, IL-18 is also able to induce severe inflammatory reactions, which suggests its role in certain inflammatory disorders. The protein encoded by this gene is a proinflammatory cytokine. This cytokine can induce the IFN-gamma production of T cells. The combination of this cytokine and IL12 has been shown to inhibit IL4 dependent IgE and IgG1 production, and enhance IgG2a production of B cells. IL-18 bindipg protein (IL18BP) can specifically interact with this cytokine, and thus negatively regulate its biological activity.
Principle of the Assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to IL-18. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody prepahumanion specific for IL-18 and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3'5, 5' tetramethyl-benzidine) substhumane solution is added to each well. Only those wells that contain IL-18, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a chapge in color. The enzyme-substhumane reaction is terminated by the addition of a sulphuric acid solution and the color chapge is measured spectrophotometrically at a wavelepgth of 450 nm +/- 2 nm. The concenthumanion of IL-18 in the samples is then determined by comparipg the O.D. of the samples to the standard curve