Interleukin 18 (IL-18) is an 18 kDa cytokine which is identified as a costimulatory factor for production of interferon-r (IFN-r) 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-1b 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 dendritic cells, activated macrophages, Kupffer cells, keratinocytes, intestinal epithelial cells, osteoblasts, adrenal cortex cells and murine diencephalons. IFN-r is produced by activated T and NK cells and plays critical roles in the defense against microbial pathogens. IFN-g activates macrophages, enhances NK activity and B cell maturation, proliferation and Ig secretion, induces MHC class I and II antigens expression, and inhibits osteoclast activation. IL-18 acts on T helper 1-type (Th1) cells, and in combination with IL-12 strongly induces production of IFN-g by these cells. Pleiotropic effects of IL-18 have also been reported, including enhancement production of IFN-g and GM-CSF in peripheral blood mononuclear cells, production of Th1 cytokines, IL-2, GM-CSF and IFN-g in T cells, enhancement of Fas ligand expression by Th1 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. Following incubation unbound samples are removed during a wash step, and then a detection antibody specific for IL-18 is added to the wells and binds to the combination of capture antibody-IL-18 in sample. Following a wash to remove any unbound combination, and enzyme conjugate is added to the wells. Following incubation and wash steps a substrate is added. A coloured product is formed in proportion to the amount of IL-18 present in the sample. The reaction is terminated by addition of acid and absorbance is measured at 450nm. A standard curve is prepared from seven IL-18 standard dilutions and IL-18 sample concentration determined.

Figure 1:Schematic diagram of the assay

1. Aluminium pouches with a Microwell Plate coated with antibody to human IL-18 (8x12)

2. 2 vials human IL-18 Standard lyophilized,2500 pg/ml upon reconstitution

3. 2 vials concentrated Biotin-Conjugate anti-human IL-18 antibody

4. 2 vials Streptavidin-HRP solution

5. 1 bottle Standard /sample Diluent

6. 1 bottle Biotin-Conjugate antibody Diluent

7. 1 bottle Streptavidin-HRP Diluent

8. 1 bottle Wash Buffer Concentrate 20x (PBS with 1% Tween-20)

9. 1 vial Substrate Solution

10. 1 vial Stop Solution

11. 4 pieces Adhesive Films

12. package insert

NOTE: [96 Tests]

Unopened Kit：Store at 2 -8° C. Do not use past kit expiration date. opened/ReconstitutedReagents：Please refer to the datasheets for detail information.

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