CD56bright NK cells exhibit potent antitumor responses following IL-15 priming
Julia A. Wagner, … , Hing C. Wong, Todd A. Fehniger
Julia A. Wagner, … , Hing C. Wong, Todd A. Fehniger
Published October 3, 2017
Citation Information: J Clin Invest. 2017;127(11):4042-4058. https://doi.org/10.1172/JCI90387.
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Research Article Immunology Oncology

CD56bright NK cells exhibit potent antitumor responses following IL-15 priming

Abstract

NK cells, lymphocytes of the innate immune system, are important for defense against infectious pathogens and cancer. Classically, the CD56dim NK cell subset is thought to mediate antitumor responses, whereas the CD56bright subset is involved in immunomodulation. Here, we challenge this paradigm by demonstrating that brief priming with IL-15 markedly enhanced the antitumor response of CD56bright NK cells. Priming improved multiple CD56bright cell functions: degranulation, cytotoxicity, and cytokine production. Primed CD56bright cells from leukemia patients demonstrated enhanced responses to autologous blasts in vitro, and primed CD56bright cells controlled leukemia cells in vivo in a murine xenograft model. Primed CD56bright cells from multiple myeloma (MM) patients displayed superior responses to autologous myeloma targets, and furthermore, CD56bright NK cells from MM patients primed with the IL-15 receptor agonist ALT-803 in vivo displayed enhanced ex vivo functional responses to MM targets. Effector mechanisms contributing to IL-15–based priming included improved cytotoxic protein expression, target cell conjugation, and LFA-1–, CD2-, and NKG2D-dependent activation of NK cells. Finally, IL-15 robustly stimulated the PI3K/Akt/mTOR and MEK/ERK pathways in CD56bright compared with CD56dim NK cells, and blockade of these pathways attenuated antitumor responses. These findings identify CD56bright NK cells as potent antitumor effectors that warrant further investigation as a cancer immunotherapy.

Authors

Julia A. Wagner, Maximillian Rosario, Rizwan Romee, Melissa M. Berrien-Elliott, Stephanie E. Schneider, Jeffrey W. Leong, Ryan P. Sullivan, Brea A. Jewell, Michelle Becker-Hapak, Timothy Schappe, Sara Abdel-Latif, Aaron R. Ireland, Devika Jaishankar, Justin A. King, Ravi Vij, Dennis Clement, Jodie Goodridge, Karl-Johan Malmberg, Hing C. Wong, Todd A. Fehniger

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Figure 9

The Ras/Raf/MEK/ERK pathway is required for IL-15 priming of CD56bright and CD56dim NK cell antitumor responses, whereas the PI3K/Akt/mTOR pathway is selectively required for CD56bright NK cell priming.

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The Ras/Raf/MEK/ERK pathway is required for IL-15 ...
(A and B) Purified NK cells were cultured for 12–16 hours in media alone (control, Con) or media plus 5 ng/ml IL-15 (primed). In addition, 1 hour before addition of IL-15, primed NK cells were treated with small-molecule inhibitors of PI3K (Ly294002) or MEK (PD98059) at various concentrations. Summary data show mean ± SEM CD107a, IFN-γ, or TNF percentage positive control, primed, or primed in the presence of PI3K (A) or MEK (B) inhibitors CD56bright and CD56dim NK cells. n = 8 normal donors, 3 independent experiments. (C–E) Flow-sorted CD56bright NK cells were cultured with or without (no inhibitor, NI) small-molecule inhibitors of PI3K (Ly294002, Pi) and MEK (PD98059, Mi) for 1 hour prior to 12–16 hours of IL-15 priming. Cells were then washed and incubated with K562 tumor targets for 6 hours at a 5:1 E:T ratio. (C) Summary data show mean ± SEM CD107a, IFN-γ, or TNF percentage positive cells. n = 9 normal donors, 6 independent experiments. (D) CD56bright NK cells were assessed for granzyme B and perforin expression via intracellular flow cytometry. Representative histogram plots show per-cell cytotoxic protein expression. Summary data show mean ± SEM granzyme B or perforin MFI. n = 11 normal donors, 6 independent experiments. (E) CD56bright NK cells were incubated with K562 tumor targets (E:T = 2.5:1) in a 4-hour flow-based killing assay. Summary data show mean ± SEM percentage specific killing. n = 12 normal donors, 8 independent experiments. Data were compared using (A and B) a paired Student’s t test or (C–E) a 1-way repeated-measures ANOVA with Tukey’s multiple-comparisons testing. *P < 0.05, **P < 0.01, ***P < 0.001.