Figure 1. Id3 expression separates Treg cells into two a transcriptionally distinct populations.

(a) Id3 expression in splenic Treg cells (CD4⁺CD25⁺CD45RB^lo) from naive Id3^GFP/+ mice using flow cytometry (left) and quantification of the percentage of Id3^lo and Id3^hi cells among splenic Treg cells (right). Each symbol represents an individual mouse and horizontal lines are the mean. (b) Foxp3 expression of sorted Id3^lo and Id3^hi splenic Treg cells (CD4⁺CD25⁺CD45RB^lo) from naive Id3^GFP/+ mice by flow cytometry. (c) Volcano plot comparing the p-value versus log2 fold-change in gene expression of Id3^hi versus Id3^lo Treg cells. (d) Volcano plot from (c) with canonical Treg cell signature genes [30] highlighted in red. Pie chart shows the number of Treg cell signature genes up-regulated more than 4-fold in Id3^lo (blue) or Id3^hi (yellow) Treg cells.