Reduction of peripheral Foxp3⁺ CD4⁺ T cells with tissue-specific decrease of Stat5a/b levels. (A) CD25 and Foxp3 expression were analyzed in sorted CD4⁺ SP splenocytes from Stat5^fl/fl mice and YFP⁺CD4⁺ SP splenocytes from Stat5^fl/−, CD4Cre, Yfp mice. Numbers indicate the percentage of CD25⁺ or FoxP3⁺ cells delineated by the rectangles. (B) Average proportion of CD4⁺ SP splenocytes. (C) Mean percentage of Foxp3⁺ CD4⁺ T cells. (D) Average total numbers of splenocytes. (E) Absolute numbers of Foxp3⁺ CD4 T cells. Means ± SE (n = 6) are shown (*P < .01).