Figure 5.

IL-15 augments NK cell metabolic activation and proliferation via PI3K–PDK1–mTOR signaling. Splenocytes from PDK1^fl/fl or PDK1^fl/fl/Vav1-Cre⁺ mice were stimulated with recombinant IL-15–IL-15R complexes overnight. (A) Expression of CD71 and CD98 was detected by flow cytometry (left) and was quantified as mean fluorescence intensity. The results are presented relative to unstimulated cells, set as 1 (right). Data represent the mean ± SEM of 5 mice per group. **, P < 0.005. (B). Intracellular phosphorylated S6, AKT T₃₀₈, and AKT S₄₇₃ were detected by flow cytometry (left), and the MFI was calculated. The protein expression levels in PDK1 ^fl/fl NK cells are presented relative to PDK1^fl/fl/Vav1-Cre⁺ mice, set as 1 (right). Data represent the mean ± SEM of 3 mice per group. Data are representative of two independent experiments. **, P < 0.005. (C) WT bone marrow cells were stimulated with recombinant IL-15–IL-15R complexes overnight in the presence of the indicated pharmacological inhibitors or DMSO, as a negative control. Flow cytometry was used to detect CD71 and CD98, and quantification is presented as the MFI. Data represent the mean ± SEM of 3 independent experiments. **, P < 0.005, ***, P < 0.0005. (D) WT mice were injected with IL-15–IL-15R complexes every 3 d together with the mTOR inhibitor Torin1 or DMSO. The absolute number of peripheral blood CD3⁻NKp46⁺NK cells was quantified on the indicated days. Fold change was calculated as describe in Fig. 3 D. Data represent the mean ± SEM of 3 mice per time point and are representative of two independent experiments. *, P < 0.05.