Recombinant Human Interleukin-18 (IL18) comes from a mammalian cell expression system and is provided as a full-length, mature protein, which appears to maintain native conformation and functionality. This tag-free preparation shows a purity level exceeding 95% as confirmed by SDS-PAGE analysis. It demonstrates biological activity by inducing IFN-gamma secretion in KG?1 human acute myelogenous leukemia cells when TNF-alpha is present, with an ED50 of approximately 2.0 ng/mL. The endotoxin level sits at approximately 10 EU/mg, determined by the LAL method, suggesting it's suitable for research applications.
Interleukin-18 (IL-18) is a pro-inflammatory cytokine that seems to play a crucial role in both innate and adaptive immunity. It's involved in triggering IFN-gamma production, which is important for activating immune cells like macrophages and natural killer cells. IL-18 takes part in various immune responses and is studied extensively for its role in immune regulation. There's also growing interest in its potential implications in inflammatory diseases and cancer research.
Potential Applications
Note: The applications listed below are based on what we know about this protein's biological functions, published research, and experience from experts in the field. However, we haven't fully tested all of these applications ourselves yet. We'd recommend running some preliminary tests first to make sure they work for your specific research goals.
1. IFN-gamma Induction Assays for Immunological Research
This application is highly valid and well-supported. The recombinant IL-18 has been rigorously validated in a functional bioassay measuring its ability to induce IFN-γ secretion in KG-1 cells with TNF-α co-stimulation, with a defined ED?? (≤2.0 ng/mL). This makes it an excellent reagent for studying IL-18-mediated immune responses. The high purity and low endotoxin level are crucial for reliable results in sensitive cell-based assays, minimizing non-specific activation. Researchers can confidently use this protein to investigate IFN-γ induction mechanisms in various immune cell types, using the provided ED?? as a precise starting point for dose-response experiments.
2. Cytokine Synergy Studies
This application is directly supported by the validation data. The confirmed synergy with TNF-α in the activity assay establishes this protein as ideal for studying cooperative effects with other cytokines (e.g., IL-12, IL-15) on immune cell activation, cytokine production, and signaling pathway crosstalk. The mammalian expression system ensures the presence of correct post-translational modifications necessary for authentic receptor binding and function, making it highly suitable for dissecting complex inflammatory networks.
3. Antibody Development and Validation
This application is extremely well-suited. The combination of high purity, confirmed bioactivity, tag-free structure, and low endotoxin makes this recombinant IL-18 an ideal immunogen for generating high-quality polyclonal or monoclonal antibodies. Crucially, the known bioactivity enables the functional screening and validation of neutralizing antibodies using the same KG-1 cell-based assay, allowing for the direct identification of antibodies that block IL-18's biological function, which is a significant advantage.
4. Protein-Protein Interaction Studies
This application is feasible, with a minor clarification. The confirmed bioactivity strongly indicates that the recombinant IL-18 protein is correctly folded, making it suitable for studying interactions with its native receptors (IL-18Rα and IL-18Rβ) and binding proteins (e.g., IL-18BP). The high purity is essential for techniques like surface plasmon resonance (SPR) to minimize background. Because the protein is tag-free, immobilization for SPR or BLI would require strategies other than His-tag capture (e.g., amine coupling, or capture via a previously validated antibody).
Final Recommendation & Action Plan
This recombinant IL-18 is a high-quality, functionally validated reagent suitable for all the proposed applications. The immediate plan should be to utilize it directly for mechanistic studies on IFN-γ induction (Application 1) and cytokine synergy (Application 2), leveraging the precise ED?? value for experimental design. It is highly recommended for antibody development efforts (Application 3), specifically for generating function-blocking antibodies. For interaction studies (Application 4), the protein is excellent, but researchers should plan an appropriate immobilization strategy that does not rely on an affinity tag, such as direct covalent coupling to a biosensor chip surface. The high purity and low endotoxin levels ensure reliable data across all these sensitive immunological and biochemical assays.
