Fig. 1: IL-2 expression in mouse and human conventional and FOXP3⁺ CD4 T cells.

Mouse splenocytes (wildtype C57Bl6/J, n = 4) and healthy human PBMC (n = 5) were stained for CD3, TCRγδ [mouse], CD4, FOXP3 and IL-2 along with a viability dye. Representative flow plots depicting IL-2 expression in mouse (top) and human (bottom) conventional T cells (T_conv, blue) (live CD3⁺ TCRγδ^neg [mouse] CD4⁺ FOXP3^neg) and T_reg (red) (live CD3⁺ TCRγδ^neg [mouse] CD4⁺ FOXP3⁺). The frequency of IL-2⁺ cells of FOXP3^neg and FOXP3⁺ cells is shown (mean ± SEM). The geometric mean fluorescence intensities of IL-2 as a measure to compare per cell protein levels between T_conv and T_reg are 2958 ± 160 (mouse T_conv) vs 2130 ± 125 (mouse T_reg) and 7308 ± 904 (human T_conv) vs 5555 ± 452 (human FOXP3^pos cells) (mean ± SEM). Ethical approvals were obtained from the KU Leuven Animal Ethics Committee (150/2019) and the University Clinic Leuven Ethical Committee (S65883). Antibodies were purchased from BD Biosciences (564667, 566405, 624295), Biolegend (100225, 503840, 320214), Miltenyi Biotec (130–111–601), and ebioscience (65-0865-18, 56-0038-80, 48-0048-42).