Extended Data Fig. 3: Environmental serine differentially supports human and mouse NK cell functions.

(a) Relative intracellular serine abundance in human and mouse NK cells cultured in Ser+ or Ser- media with IL-2/15 (human) or IL-15 (mouse) for 72 h before metabolite extraction. (b) Representative histograms (left) and quantification (right) of MFI of granzyme B (GzmB) and perforin of Ser+ or Ser- human NK cells after 48 h culture. FMO, fluorescence minus one control. (c) Representative histograms (left) and quantification (right) of percent CD107a⁺ and MFI of CD107a⁺ cells of Ser+ or Ser- human NK cells after 48 h culture followed by 4 h stimulation with K562 cells and IL-2/15 in the presence of anti-CD107a antibody, brefeldin A, and monensin. (d) MFI of GzmB and perforin of Ser+ or Ser- mouse NK cells stimulated with anti-Ly49H platebound antibody. (e) Quantification of percent CD107a⁺ and MFI of CD107a⁺ cells of Ser+ or Ser- mouse NK cells stimulated with anti-Ly49H platebound antibody. (f) MFI of phosphorylated pAKT^T308, pS6^S235/236, or pAKT^S473 in naïve or D3 IL-15-activated mouse NK cells. Data represent mean ± SEM or individual paired donors across at least two independent experiments. Data are representative of (a) n = 3, (b) n = 5, and (c) n = 7 independent human donors, and (a) n = 4, (d, f) n = 8 and (e) n = 6 independent mice. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 by (a, d, e) two-way ANOVA or (b, c, f) two-sided paired t-test. Exact p-values: (a) p = 0.0003 human ser+ vs ser-, p = 0.0021 mouse ser+ vs ser-, p = 0.0014 human ser- vs mouse ser-; (b) p = 0.0087, p = 0.0419; (c) p = 0.0181, p < 0.0001; (d) p = 0.0005; (e) p = 0.0318, p < 0.0001; (f) p = 0.0275, p = 0.0002, p = 0.0286.