Recombinant Human IL-18Rα-Fc Chimera (carrier-free)

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Regulatory Status
Other Names
Interleukin-18 receptor 1, IL-18R-1, IL-18R1, CD218 antigen-like family member A, CD218a, CDw218a, IL1 receptor-releated protein, IL-1Rrp, IL-18R-alpha, IL-18Ralpha, Interleukin-18 receptor alpha, IL-18Ra, IL-1R5
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Product Citations
Recombinant human IL-18Rα-Fc chimera inhibits the induction of IFN-γ by human IL-18 in human KG-1 cells. The ED50 for this effect is 1 - 5 µg/mL.
  • Human_IL-18Ralpha_CF_RECOM_1_113020.png
    Recombinant human IL-18Rα-Fc chimera inhibits the induction of IFN-γ by human IL-18 in human KG-1 cells. The ED50 for this effect is 1 - 5 µg/mL.
  • Human_IL-18Ralpha_CF_RECOM_2_113020.png
    Stability Testing for Recombinant Human IL-18Rα-Fc chimera. Recombinant human IL-18Rα-Fc chimera was aliquoted in PBS, pH7.2 at 0.2 mg/mL. One aliquot was frozen and thawed four times (4x Freeze/Thaw) and compared to the control that was kept at 4⁰C (Control). The samples were tested for their ability to inhibit the induction of IFN-γ by human IL-18 in human KG-1 cells. The ED50 for this effect is 1 - 5 µg/mL.
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790304 25 µg 147 CHF
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790306 100 µg 335 CHF
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790308 500 µg 996 CHF
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IL-18 is essential for both innate and adaptive immunity. The IL-18 receptor is composed of an α and a β subunit that form a high affinity heterodimer for IL-18. IL-18R1, also known as IL-18Rα chain and CD218a, is a type I transmembrane protein. It is expressed on NK cells, neutrophils, endothelial cells, and subsets of T and B cells. The expression of IL-18R1 and IL-18RAcP (IL-18Rβ) on lymphocytes are upregulated upon IL-12 stimulation. IL-23 and IL-18 synergistically enhance IL-18R1 expression on NK-like T cells. Upon IL-18 engagement, the intracellular TIR domain of IL-18R1 and IL-18RAcP recruits adaptor proteins, MyD88, and in turn recruits IRAK and TRAF6, activating NF-κB and MAPK pathways, which upregulates production of various inflammatory cytokines. The interaction of IL-18 and IL-18 receptor has been reported to be implicated in promotion of Th1 cytokine production and atherogenesis. IL-37 also binds to IL-18R1, but recruits IL-1R8 (SIGIRR) to activate anti-inflammatory responses.

Product Details
Technical Data Sheet (pdf)

Product Details

Human IL-18Rα, amino acid Glu20-Arg329 (Accession #Q13478.1), with a linker (SR) and a C-terminal human IgG (Pro100-Lys330) and a 6His tag, was expressed in CHO cells.
Molecular Mass
The 549 amino acid recombinant protein has a predicted molecular mass of approximately 62.7 kD. The DTT-reduced and non-reduced protein migrates at approximately 95 kD and 190 kD by SDS-PAGE, respectively. The predicted N-terminal amino acid is Glu.
> 95%, as determined by Coomassie stained SDS-PAGE
0.22 µm filtered protein solution in PBS.
Endotoxin Level
Less than 0.01 ng per µg cytokine as determined by the LAL method.
25 µg size is bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration and expiration, please enter the lot number in our Certificate of Analysis online tool.
Storage & Handling
Unopened vial can be stored between 2°C and 8°C for up to 2 weeks at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
The ED50 is 1 - 5 μg/mL, as determined by a dose-dependent inhibition of human IL-18-induced IFN-γ secretion by KG-1 cells in the presence of 10 ng/mL of human IL-18 (Cat. No. 592102) and 30 μg/mL of human IL-18RAcP (IL-18Rβ).


Application Notes

BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are validated in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at

Antigen Details

Disulfide-linked homodimer

Expressed on NK cells and neutrophils, IL-12 activated T and B cells, endothelial cells, and smooth muscle cells; highly expressed on Hodgkin's disease cell lines.

IL-18Rα forms a receptor complex with IL-18Rβ and mediates IL-18 function.
Human IL-18Rα inhibits the induction of IFN-γ by human IL-18 in human KG-1 cells.
Antigen References

1. Torigoe K, et al. 1997. J. Biol. Chem. 272: 25737. 
2. Born TL, et al. 1998. J. Biol. Chem. 273: 29445. 
3. Airoldi I, et al. 2000. J. Immunol. 165: 6880.
4. van de Wetering D, et al. 2008. Int. Immunol. 21: 145.
5. Adachi O, et al. 1998. Immunity. 9: 143. 
6. Tsutsumi N, et al. 2014. Nat. Comm. 5: 5340.

Gene ID
8809 View all products for this Gene ID
View information about IL-18Ralpha on

Related FAQs

Why choose BioLegend recombinant proteins?

     • Each lot of product is quality-tested for bioactivity as indicated on the data sheet.
     • Greater than 95% Purity or higher, tested on every lot of product.
     • 100% Satisfaction Guarantee for quality performance, stability, and consistency.
     • Ready-to-use liquid format saves time and reduces challenges associated with reconstitution.
     • Bulk and customization available. Contact us.
     • Learn more about our Recombinant Proteins.

How does the activity of your recombinant proteins compare to competitors?

We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!

What is the specific activity or ED50 of my recombinant protein?

The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.

Have your recombinants been tested for stability?

Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.

Does specific activity of a recombinant protein vary between lots?

Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.

How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?

Use formula Specific activity (Units/mg) = 10^6/ ED50 (ng/mL)

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For research use only. Not for diagnostic use. Not for resale. BioLegend will not be held responsible for patent infringement or other violations that may occur with the use of our products.


*These products may be covered by one or more Limited Use Label Licenses (see the BioLegend Catalog or our website, BioLegend products may not be transferred to third parties, resold, modified for resale, or used to manufacture commercial products, reverse engineer functionally similar materials, or to provide a service to third parties without written approval of BioLegend. By use of these products you accept the terms and conditions of all applicable Limited Use Label Licenses. Unless otherwise indicated, these products are for research use only and are not intended for human or animal diagnostic, therapeutic or commercial use.


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