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 3

IL-15–primed CD56bright NK cells have enhanced cytotoxicity.

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IL-15–primed CD56bright NK cells have enhanced c...
(A) Control or primed purified NK cells were assessed for expression of intracellular granzyme B and perforin and cell surface TRAIL using flow cytometry. Representative histograms gated on CD56bright NK cells show per-cell protein expression, with gray histograms depicting unstained cells. Summary data show mean ± SEM granzyme B and perforin median fluorescent intensity (MFI), or TRAIL percentage positive CD56bright NK cells. n = 4–6 normal donors, 2–3 independent experiments. (B and C) Control or primed flow-sorted CD56bright and CD56dim NK cells were assessed for cytotoxicity against K562 leukemia cells in a 4-hour flow-based killing assay. (B) Summary data show mean ± SEM percentage specific killing by control or primed NK cell subsets at the indicated E:T ratios. (C) Summary data show mean ± SEM specific killing at the 2.5:1 E:T ratio. n = 4 normal donors, 2 independent experiments. (D) Representative confocal Z-stack images show CD107a (LAMP1) and granzyme B (Gzm B) in flow-sorted, control or IL-15–primed CD56bright NK cells. Representative images were contrast-enhanced for better visualization. (E) Summary data show mean ± SEM LAMP1 and granzyme B single-cell mean pixel intensity × area, quantified from focal planes in the middle of cells (control n = 20–32, primed n = 25–37) from 5 normal donors. Data were compared using (A and E) a paired Student’s t test or (B and C) a 1-way repeated-measures ANOVA, with Bonferroni’s multiple-comparisons testing of indicated groups. *P < 0.05, **P < 0.01, ***P < 0.001.