A complex production landscape for IL-2 in the homeostatic immune system. (A) IL-2 expression in spleen, LN, and lung from WT cells stimulated ex vivo with PdBU/ionomycin for 4 h. n = 6–9. pDC, plasmacytoid DC. (B) Frequency of each annotated cell type among the total IL-2⁺ population following ex vivo stimulation. (C) Radar plot of frequency (log₁₀) of IL-2⁺ population following ex vivo stimulation. (D) RFP expression in spleen, LN, and lung from Il2^creRosa^RFP mice. n = 6. (E) Frequency of each annotated cell type among the total RFP⁺ population from Il2^creRosa^RFP mice. (F) Radar plot of frequency (log₁₀) of RFP⁺ population. (G) IL-2 expression in spleen, LN, and lung of IL-2^GFP mice. n = 6. (H) Frequency of each annotated cell type among the total GFP⁺ population from IL-2^GFP mice. (I) Radar plot of frequency (log₁₀) of GFP⁺ population. (J) Expression of low-affinity (CD25⁺), intermediate-affinity (CD122⁺), or high-affinity (CD25⁺CD122⁺) IL-2 receptors in spleen, LN, and lung WT cells. n = 10. (K) Genetic construct of Rosa^IL-2 mice. (L) Representative histogram of GFP and IL-2 expression in CD4⁺ Tconv from WT and CD4^creRosa^IL-2 mice incubated for 4 h in the presence of BrefA or WT CD4⁺ Tconv stimulated for 4 h with PdBU/ionomycin/BrefA. (M) Geometric mean fluorescence intensity (gMFI) of IL-2 expression from ex vivo–stimulated WT mice or nonstimulated CD4^creRosa^IL-2 mice. n = 5. Data are representative of (A, B, G–I, L, and M) or pooled from (C and D) at least two independent experiments.