Cloning Of The CDNA For Human IL-18 Mature Peptide, Expressing In Two Escherichia Coli Expression System, And The Biologic Activities Of The Expressed Protein

Interleukin-18 (IL-18) was first purified by Okamura in 1995 from the livers of mice treated with the bacterium P. acnes and subsequently challenged with lipopolysaccharide (LPS) to induce toxic shock. Because it can induce the producing of IFN-γ by the Thl cell, it was first called interferon-γ -inducing factor, then it is named interleukin-18 in 1996. A cDNA of human IL-18 cloned by cross-hybridization from human liver cDNA libraries was found to contain a single open reading frame encoding a 193-amino-acid proIL-18. ProIL-18 has no N-glyco site and conventional signal peptide. It has been shown that the biological inactive proIL-18 is cleaved with interleukin-1β (IL—1 β )-converting enzyme (ICE) at the authentic processing site, Asp-X, to generate the mature active form of IL-18. Human IL-18 is mainly produced by peripheral blood mononuclear cells (PBMC) and macrophages. IL-18 enhances cytotocity of NK and proliferation of T cells. It stimulates Thl cells to produce IL—2 and IFN- γ. This effect is augmented by IL—12 in a synergistic manner. In addition, IL-18 can augments the production of GM-CSF and decreases IL-10 production but not effect on IL-4 secretion by PBMC.Human interleukin-18 cDNA is expressed in many organs and tissues, such as thymus, liver and active macrophages. In order to identify the expressing situation of IL-18 in Chinese, the Chinese IL-18 mature peptide cDNA was obtained respectively from adult PBMC, adult bone marrow cDNA libray, adult tonsil cDNA library, Embryonic cerebrum and cerebellum aged 3monthes and aged...