Fig. 7.

T_reg cells receiving limited IL-2 signals cannot suppress autoreactive WT T_conv cells: a Foxp3^y/− Cd45.1^+/+ neonate mice were transferred i.p. with 10⁶ Il2ra^mut/mut or WT flow-purified Foxp3^Rfp/Rfp CD3⁺CD4⁺ T_reg cells and survival was monitored over 120 days. Graphs average results over multiple mice in each group and 7-16 replicate experiments. b, c Rag1^−/− mice received 5 × 10⁵ flow-purified Foxp3^Rfp/Rfp CD3⁺CD4⁺ T_reg cells together with 1.5 × 10⁶ WT CD3⁺CD4⁺CD25^neg T_conv cells i.v. Weight loss was monitored up to 61 days post transfer and immune cell infiltrates on H/E stained sections is shown at day 61 (n = 4). d Numbers of transferred Foxp3^Rfp/Rfp CD3⁺CD4⁺ T_reg cells in the spleen and lung of Rag1^−/− mice (left bar graphs) and proportion of cytokine-secreting CD3⁺CD4⁺ T_conv cells 4 h post PMA/ionomycin stimulation. e Foxp3 expression in Foxp3^Rfp/Rfp CD3⁺CD4⁺ T_reg cells 45 and 75 days post transfer, proportion and absolute numbers of ex-T_reg cells in LNs and spleens. f, g Schematic of mixed bone-marrow chimera generation in lethally irradiated WT B6 recipient mice with discriminative congenic markers. f, g Representative FACS dot plots of Foxp3 and CD4 expression in blood T cells of f WT/Il2ra^mut/mut and g Foxp3^y/−/WT and Foxp3^y/−/Il2ra^mut/mut chimeras 10 and 6 weeks post reconstitution, respectively. Graph in f shows the ratio of WT vs Il2ra^mut/mut T_conv and T_reg cells for each individual chimera. Data are across several chimeras (5–9 mice/group) in 3–4 replicate experiments. h, i Spleen, LN pictures, and H/E stained sections of lung, liver, pancreas, and small intestine from Foxp3^y/−/WT and Foxp3^y/−/Il2ra^mut/mut chimeras. j Cells from indicated organs from the two groups of chimeras were stained for cell-surface expression of CD3, CD4, CD8, CD62L, KLRG1, and CD44. Bar graphs show the proportion of activated CD4⁺ (CD44⁺CD62L^lo) or CD8⁺ (KLRG1⁺CD62L^lo) T cells (n = 5–9). k Proportion of activated CD3⁺CD4⁺ or CD8⁺ T_conv cells from Il2ra^mut/mut or WT BM in Foxp3^y/−/Il2ra^mut/mut chimeras. Bar graphs summarize average proportion across mice (n = 5–9). p-values are indicated when relevant with *p < 0.05; **p < 0.01; ***p < 0.001; NS not significant, using two-tailed unpaired Student’s t-test. Symbols on bar graphs feature individual mice