Interleukin-18 (IL-18, IFN-gamma inducing factor, IGIF), rat recombinant (rrIL-18)

Interleukin-18 is a member of the interleukin-1 family of cytokines with pro-inflammatory and tumor-suppressive properties. Its ability to potently enhance the production of interferon-gamma indicates in particular the crucial function of interleukin-18 as an immunomodulatory molecule. In fact, high levels of interleukin-18 are detected in human diseases associated with immunoactivation including viral or bacterial infections and chronic inflammation. Animal models suggest suppression of interleukin-18 bioactivity as a novel therapeutic concept specifically for the treatment of chronic inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis. It is the only cytokine with a unique capacity to induce T helper 1 or T helper 2 polarization, depending on the immunologic context. Description: Recombinant Rat IL-18 produced in E.Coli is a single, non-glycosylated polypeptide chain containing 158 amino acids and having a molecular mass of 18260 Dalton. Recombinant Rat Interleukin-18 is purified by proprietary chromatographic techniques. Amino Acid Sequence: The sequence of the first five N-terminal amino acids was determined and was found to be His-Phe-Gly-Arg-Leu. Dimers and Aggregates: Less than 1% as determined by silver-stained SDS-PAGE gel analysis. Biological Activity: Rat IL-18 is fully biologically active when compared to standard. The ED50 as determined by the dose-dependent stimulation of IFN-gamma by murine lymph node cells (4 x 105 cells/well) co-stimulated with sub optimal dose of ConA (0.75ug/ml) is 12 ng/ml. The medium was RPMI containing 10% FCS and 50µM 2-ME. Protein Content: Protein quantitation was carried out by two independent methods: , 1. UV spectroscopy at 280 nm using the absorbency value of 0.213 as the extinction coefficient for a 0.1% (1mg/ml) solution. This value is calculated by the PC GENE computer analysis program of protein sequences (IntelliGenetics). , 2. Analysis by RP-HPLC, using a standard solution of IL-18 as a Reference Standard. Endotoxin: < 0.1ng/ug (IEU/ug) of rat IL-18. Solubility: It is recommended to reconstitute the lyophilized IL-18 in sterile 18MOmega-cm H2O not less than 100µg/ml, which can then be further diluted to other aqueous solutions. Stability: Lyophilized Interlekin-18 although stable at room temperature for 3 weeks, should be stored desiccated below -180C. Upon reconstitution IL-18 should be stored at 40C between 2-7 days and for future use below -180C. For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA). Please avoid freeze-thaw cycles.