This immunoassay kit allows for the specific measurement of human IL-18 concentrations in cell culture supernates, serum, and plasma.
Interleukin 18 (IL-18) is a 18 kDa novel cytokine which is identified as a costimulatory factor for production of interferon-γ (IFN- γ ) in response to toxic shock. It shares functional similarities with IL-12. IL-18 is synthesized as a precursor 24 kDa molecule without a signal peptide and must be cleaved to produce an active molecule. IL-1 ß converting enzyme (ICE, Caspase-1) cleaves pro-IL-18 at aspartic acid in the P1 position, producing the mature, bioactive peptide that is readily released from the cells. It has been reported that IL-18 is produced from Kupffer cells, activated macrophages, keratinocytes, intestinal epithelial cells, osteoblasts, adrenal cortex cells and murine diencephalon.
IL-18 acts on T helper 1-type T (Th1) cells and in combination with IL-12 strongly induces production of IFN- γ by these cells. Pleiotropic effects of IL-18 have also been reported, including enhancement production of IFN- γ and GM-CSF in peripheral blood mononuclear cells, production of T helper type 1 cytokines, IL-2, GM-CSF and IFN-γ in T cells, enhancement of Fas ligand expression by T helper type 1 cells.
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal 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. An enzyme-linked monoclonal antibody specific for IL-18 is added to the wells. Following a wash to remove any unbound antibody-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.