Induced CD8α identifies human NK cells with enhanced proliferative fitness and modulates NK cell activation
Celia C. Cubitt, … , Jacqueline E. Payton, Todd A. Fehniger
Celia C. Cubitt, … , Jacqueline E. Payton, Todd A. Fehniger
Published May 28, 2024
Citation Information: J Clin Invest. 2024;134(15):e173602. https://doi.org/10.1172/JCI173602.
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Research Article Immunology

Induced CD8α identifies human NK cells with enhanced proliferative fitness and modulates NK cell activation

Abstract

The surface receptor CD8α is present on 20%–80% of human (but not mouse) NK cells, yet its function on NK cells remains poorly understood. CD8α expression on donor NK cells was associated with a lack of therapeutic responses in patients with leukemia in prior studies, thus, we hypothesized that CD8α may affect critical NK cell functions. Here, we discovered that CD8α– NK cells had improved control of leukemia in xenograft models compared with CD8α+ NK cells, likely due to an enhanced capacity for proliferation. Unexpectedly, we found that CD8α expression was induced on approximately 30% of previously CD8α– NK cells following IL-15 stimulation. These induced CD8α+ (iCD8α+) NK cells had the greatest proliferation, responses to IL-15 signaling, and metabolic activity compared with those that sustained existing CD8α expression (sustained CD8α+) or those that remained CD8α– (persistent CD8α–). These iCD8α+ cells originated from an IL-15Rβhi NK cell population, with CD8α expression dependent on the transcription factor RUNX3. Moreover, CD8A CRISPR/Cas9 deletion resulted in enhanced responses through the activating receptor NKp30, possibly by modulating KIR inhibitory function. Thus, CD8α status identified human NK cell capacity for IL-15–induced proliferation and metabolism in a time-dependent fashion, and its presence had a suppressive effect on NK cell–activating receptors.

Authors

Celia C. Cubitt, Pamela Wong, Hannah K. Dorando, Jennifer A. Foltz, Jennifer Tran, Lynne Marsala, Nancy D. Marin, Mark Foster, Timothy Schappe, Hijab Fatima, Michelle Becker-Hapak, Alice Y. Zhou, Kimberly Hwang, Miriam T. Jacobs, David A. Russler-Germain, Emily M. Mace, Melissa M. Berrien-Elliott, Jacqueline E. Payton, Todd A. Fehniger

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Figure 1

Sorted CD8α– NK cells have enhanced tumor control in vivo.

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Sorted CD8α– NK cells have enhanced tumor control in vivo. (A) Represent...
(A) Representative flow plot showing CD8α expression on CD56bright and CD56dim NK cells. (B). Percentage of freshly isolated healthy donor human NK cells that expressed CD8α. (C) Percentage of freshly isolated NK cells, gated into CD56bright or CD56dim cells, that expressed CD8α. n = 49. ****P < 0.0001, by 2-tailed, paired Student’s t test. (D–F) CD56dimCD8α+ and CD56dimCD8α– NK cells were sorted from primary human NK cells and rested overnight in 1 ng/mL IL-15. The next day, approximately 1 × 106 to 2 × 106 CD8α+ CD56dim or CD8α–CD56dim NK cells were injected i.v. via the tail vein into NSG mice (Day –1). The following day (Day 0), 0.4 × 106 to 0.5 × 106 K562-CBR-luciferase (K562-luc) cells were injected i.v. into the tail vein. NK cells were supported with i.p. rhIL-15 three times/week, and tumor burden was assessed via BLI on days 1, 4, 7, 11, and 15 after tumor injection. (D) Experimental schema. (E) Representative BLI images from 1 of 3 independent experiments on day 15 and (F) summary data showing tumor burden as the mean ± SEM within the indicated groups. n = 5 unique donors; n = 3 independent experiments; n = 8–10 mice in each group. *P < 0.05 and ****P < 0.0001, by mixed-effects model with Holm-Šídák correction for multiple comparisons.