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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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 6

iCD8α NK cells have greater IL-15R expression and signaling.

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iCD8α NK cells have greater IL-15R expression and signaling. (A) Primary...
(A) Primary human NK cells were sorted into CD8α+CD56dim and CD8α–CD56dim populations and cultured in vitro in 1 ng/mL IL-15 for 6 days. CD132 and CD122 expression was assessed by flow cytometry, gated within the indicated subsets. n = 7 donors and 3 independent experiments. (B and C) CD56dim NK cells were sorted from freshly isolated primary human NK cells, based on high and low expression of CD122 and CD8α, and cultured for 6 days in vitro in 5 ng/mL IL-15. (B) Representative flow plots of the gating strategy for cell sorting. (C) Summary data showing the percentage of NK cells positive for CD8α or Ki67 expression that were originally sorted as CD122hi or CD122lo and CD8α+ or CD8α–. n = 4 donors, and 2 independent experiments. (D–G) CD8α+ CD56dim and CD8α–CD56dim NK cells were sorted and cultured for 6 days in vitro with 1 ng/mL IL-15. Cells were cultured briefly (1 hour) in cytokine-free media prior to stimulation for 1 hour with the indicated concentrations of IL-15. Data are shown as the MFI and FC over the unstimulated condition within the indicated cell subsets for (D) p-ERK1/-2, (E), p-STAT5, (F) p-AKT, and (G) p-S6. n = 5 donors and 2 independent experiments. Data represent the mean ± SEM.*P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by (A and C) repeated-measures, 1-way ANOVA and (D–G) 2-way ANOVA with Holm-Šídák correction for multiple comparisons.