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This Article Full Text Full Text (PDF) All Versions of this Article: jimmunol.0901244v1 183/6/3598    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Google Scholar Articles by Zhu, X. Articles by Wong, H. C. PubMed PubMed Citation Articles by Zhu, X. Articles by Wong, H. C.

Novel Human Interleukin-15 Agonists

Xiaoyun Zhu^*, Warren D. Marcus^*, Wenxin Xu^*, Hyung-il Lee^*, Kaiping Han^*, Jack O. Egan^*, Jason L. Yovandich, Peter R. Rhode^* and Hing C. Wong^*,1

^* Altor BioScience Corporation, Miramar, FL 33025; and Biological Resources Branch, Division of Cancer Treatment and Diagnosis, National Cancer Institute-Frederick, Frederick, MD 21702

IL-15 is an immunostimulatory cytokine trans-presented with the IL-15 receptor -chain to the shared IL-2/IL-15Rβ and common -chains displayed on the surface of T cells and NK cells. To further define the functionally important regions of this cytokine, activity and binding studies were conducted on human IL-15 muteins generated by site-directed mutagenesis. Amino acid substitutions of the asparagine residue at position 72, which is located at the end of helix C, were found to provide both partial agonist and superagonist activity, with various nonconservative substitutions providing enhanced activity. Particularly, the N72D substitution provided a 4–5-fold increase in biological activity of the IL-15 mutein compared with the native molecule based on proliferation assays with cells bearing human IL-15Rβ and common -chains. The IL-15N72D mutein exhibited superagonist activity through improved binding ability to the human IL-15Rβ-chain. However, the enhanced potency of IL-15N72D was not observed with cells expressing the mouse IL-15R-IL-15Rβ-_c complex, suggesting that this effect is specific to the human IL-15 receptor. The enhanced biological activity of IL-15N72D was associated with more intense phosphorylation of Jak1 and Stat5 and better anti-apoptotic activity compared with the wild-type IL-15. IL-15N72D superagonist activity was also preserved when linked to a single-chain TCR domain to generate a tumor-specific fusion protein. Thus, the human IL-15 superagonist muteins and fusions may create opportunities to construct more efficacious immunotherapeutic agents with clinical utility.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Address correspondence and reprint requests to Dr. Hing C. Wong, Altor BioScience Corporation, 2810 North Commerce Parkway, Miramar, FL 33025. E-mail address: hingwong{at}altorbioscience.com

² Abbreviations used in this paper: scTCR, single chain T-cell receptor; CHO, Chinese hamster ovary; Su, sushi domain; _c, common -chain; hIL, human IL; mIL, mouse IL; rhIL, recombinant human IL.