Changes in Treg number and frequency after αCD25 and/or rhIL-7 in tumor-free animals. Where indicated, Thy-B and TXY C57BL/6 mice received 0.3 mg αCD25 on days −6, −3, and 0 and/or 10 μg rhIL-7 on days 0 to 28. (A) Percentage CD4⁺FOXP3⁺ Tregs in inguinal lymph nodes. (B) Absolute numbers of CD4⁺FOXP3⁺CD62L⁺ Tregs in inguinal lymph nodes. Results in panels A and B show the mean plus or minus SEM of the groups (n = 3-10/group), and results were pooled from 2 separate experiments. *P < .05, **P < .005, compared with control untreated Thy-B or TXY animals. (C) Representative fluorescence-activated cell sorter plots illustrating CD62L expression on FOXP3⁺ cells in gated CD4⁺ lymph node cells in Thy-B (left panel) and TXY hosts (right panel) at baseline and on the days indicated after αCD25. (D-E) BrdU incorporation in CD25⁺ and CD25⁻ subsets of FOXP3⁺ LN cells in (D) untreated mice and (E) 6 days after αCD25 therapy. Blue line represents BrdU-injected animals; red line, control animals. Results are representative of 3 experiments with 10 to 13 mice/group.