IL18(Interleukin18 ), previously known as interferon-gamma (IFN-gamma)-inducing factor, is an activator of NK cells and a co-inducer of Th1 cytokines. IL18 is produced from Kupffer cells, activated macrophages, keratinocytes, intestinal epithelial cells, osteoblasts, adrenal cortex cells and murine diencephalon. Recombinant mouse IL18 was expressed in E.coli and purified by conventional chromatography, after refolding of the isolated inclusion bodies in a renaturation buffer.