| 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. |
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| Catalog # | I8439-95R1 |
| 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 18M -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. |
| Molecular Weight | 18.26kD |
| Source | E. coli |
| Purity | 95% as determined by RP-HPLC, anion-exchange FPLC and/or reducing and non-reducing SDS-PAGE Silver Stained gel. |
| Concentration | ~1mg/ml |
| Form | Supplied as a lyophilized powder in 0.4X PBS, pH 7.2. |
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| Important Note | This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological. |
