IL-15:IL-15 receptor alpha superagonist complex: high-level co-expression in recombinant mammalian cells, purification and characterization.

Abstract

IL-15, a promising cytokine for treating cancer and viral diseases, is presented in trans by the IL-15 receptor (IL-15R) alpha-chain to the IL-15Rβγc complex displayed on the surface of T cells and natural killer (NK) cells. We previously reported that an asparagine to aspartic acid substitution at amino acid 72 (N72D) of IL-15 provides a 4-5-fold increase in biological activity compared to the native molecule. In this report, we describe Chinese hamster ovary (CHO) cell expression of a soluble complex (IL-15 N72D:IL-15RαSu/Fc) consisting of the IL-15 N72D superagonist and a dimeric IL-15Rα sushi domain-IgG1 Fc fusion protein. A simple but readily scalable affinity and ion exchange chromatography method was developed to highly purify the complex having both IL-15 binding sites fully occupied. The immunostimulatory effects of this complex were confirmed using cell proliferation assays. Treatment of mice with a single intravenous dose of IL-15N72D:IL-15RαSu/Fc resulted in a significant increase in CD8+ T cells and NK cells that was not observed following IL-15 treatment. Pharmacokinetic analysis indicated that the complex has a 25-h half-life in mice which is considerably longer than <40-min half-life of IL-15. Thus, the enhanced activity of the IL-15N72D:IL-15RαSu/Fc complex is likely the result of the increased binding activity of IL-15N72D to IL-15Rβγc, optimized cytokine trans-presentation by the IL-15RαSu domain, the dimeric nature of the cytokine domain and its increased in vivo half-life compared to IL-15. These findings indicate that this IL-15 superagonist complex could serve as a superior immunostimulatory therapeutic agent.

• Authors: Kai-ping Han, Xiaoyun Zhu, Bai Liu, Emily Jeng, Lin Kong, Jason L Yovandich, Vinay V Vyas, Warren D Marcus, Pierre-Andre Chavaillaz, Christian A Romero, Peter R Rhode, Hing C Wong
• Journal: Cytokine (Cytokine) Vol. 56 Issue 3 Pg. 804-10 (Dec 2011) ISSN: 1096-0023 [Electronic] England
• PMID: 22019703 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2011 Elsevier Ltd. All rights reserved.

Chemical References

• Interleukin-15
• Interleukin-15 Receptor alpha Subunit
• Mutant Proteins
• Recombinant Fusion Proteins

Topics

• Animals
• Body Weight (drug effects)
• CHO Cells
• Cell Separation
• Chromatography, Gel
• Cricetinae
• Cricetulus
• Electrophoresis, Polyacrylamide Gel
• Humans
• Interleukin-15 (agonists, isolation & purification)
• Interleukin-15 Receptor alpha Subunit (agonists, isolation & purification)
• Lymphocytes (drug effects, metabolism)
• Male
• Mammals (metabolism)
• Mice
• Mice, Inbred C57BL
• Mutant Proteins (metabolism)
• Organ Size (drug effects)
• Recombinant Fusion Proteins (genetics, metabolism, pharmacokinetics, pharmacology)
• Recombination, Genetic (genetics)