| Source: |
Escherichia coli |
| Molecular Weight: |
Approximately 18.2 kDa, a single non-glycosylated polypeptide chain containing 157 amino acids. |
| Purity: |
> 95% by SDS-PAGE analyses.> 98% by HPLC analyses. |
| Biological Activity: |
Measured by its ability to induce IFN-gamma secretion by KG‑1 human acute myelogenous leukemia cells. The ED50 for this effect is 1.5-15 ng/mL. The specific activity of recombinant human IL-18 is > 3.0 × 106 Units/mg, which is calibrated against rHuIL-18 WHO reference reagent (NIBSC code: 03/200). |
| Physical Appearance: |
Sterile filtered white lyophilized (freeze-dried) powder. |
| Formulation: |
Lyophilized from a 0.2 μm filtered solution in PBS, 0.05% Tween-20, pH7.0. |
| Endotoxin: |
Less than 0.01 EU/μg of rHuIL-18 GMP as determined by LAL method. |
| Reconstitution: |
Centrifuge the vial briefly before opening to ensure that the contents settle at the bottom. Reconstitute the vial with sterile distilled water or an aqueous buffer containing 0.1% BSA to achieve a concentration of 0.1-1.0 mg/mL. Divide the resulting stock solution into working aliquots and store them at or below -20°C. For further dilutions, use appropriate buffered solutions. |
| Stability & Storage: |
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
12 months from date of receipt, -20 to -70°C as supplied.
1 month, 2 to 8°C under sterile conditions after reconstitution.
3 months, -20 to -70°C under sterile conditions after reconstitution. |
| Background: |
Interleukin-18 (IL-18) is a cytokine that produces inflammatory reactions and belongs to the IL-1 cytokine family. Its effect on immunity varies depending on the surrounding cytokines. IL-18 is produced as a 24 kDa precursor by various cells including epithelial and endothelial cells, keratinocytes, gamma δ T cells and phagocytes. The activation of the precursor takes place inside the cell via Caspase-1 proteolysis, releasing the mature 17 kDa cytokine. The precursor can also be set free by dead cells for external cleavage by several proteases.
Infection or tissue damage can initiate the activation of IL-18, which can add to the pathology of chronic inflammation. IL-18 binds to the IL-18 R alpha receptor that is ubiquitously expressed and recruits the IL-18 R beta to form an operational receptor complex. Its bioactivity is negatively modulated by IL-18 binding proteins and homologues of IL-18BP encoded by viruses.
In presence of IL-12 or IL-15, IL-18 exaggerates anti-viral Th1 immune responses by encouraging IFN-gamma production as well as CD8+ T cells and NK cells' cytolytic activity. Without IL-12 or IL-15, IL-18 propels the production of Th2 cytokines IL-4 and IL-13 by CD4+ T cells and basophils. When combined with IL-1 beta or IL-23, IL-18 encourages the production of IL-17 by gamma δ T cells and CD4+ T cells, irrespective of the antigen.
Moreover, IL-18 assists in the maturation of dendritic cells and triggers neutrophils to burst. In the context of cancer, IL-18 can have varying effects, including enhancing anti-cancer immunity, influencing angiogenesis and promoting metastasis. The mature IL-18 in humans shares around 63% amino acid sequence identity with that of rats and mice. Notably, in human ovarian cancer, an isoform resistant to Caspase-1 activation is created through alternative splicing. An isoform can be present on the cell surface of induced macrophages by M-CSF and can be released in response to bacterial endotoxin. |
| Shipping: |
The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below. |
| Sequence: |
YFGKLESKLS VIRNLNDQVL FIDQGNRPLF EDMTDSDCRD NAPRTIFIIS MYKDSQPRGM AVTISVKCEK ISTLSCENKI ISFKEMNPPD NIKDTKSDII FFQRSVPGHD NKMQFESSSY EGYFLACEKE RDLFKLILKK EDELGDRSIM FTVQNED |
| Sterility: |
Negative. |
| Mycoplasma: |
Negative. |
| Host Cell Protein: |
Less than 0.05% when tested by ELISA. |
| Quality Statement: |
The manufacturing and testing of these products comply with ICH Q7 guidelines. |
| Host Cell DNA: |
Less than 20 ng/mg when tested by qPCR. |
| In Vitro Virus Assay: |
Negative. |
