Groups of mice were sensitized with OVA or PBS only prior to intravenously receiving unsorted (total [tot]) MLN/PP populations isolated from uninfected or neonatally infected and/or OVA-sensitized or Treg-depleted (–FoxP3⁺) donors. Tregs were depleted in foxP3-EGFP-DTR–transgenic donors by a single dose of diphtheria toxin 1 day prior to cell isolation; Treg-proficient donors were nontransgenic littermates. Additional recipients received 2.5 × 10⁵ immunomagnetically isolated, MLN/PP-derived CD4⁺CD25⁺ Tregs or CD4⁺CD25^– T cells (>85% purity each) from neonatally infected donors. All recipients as well as control groups were nebulized with OVA on days 2, 3, and 4 after adoptive transfer and sacrificed 2 days later. (A) Airway hyperresponsiveness in response to increasing doses of inhaled methacholine and the highest dose of 100 mg/ml, respectively. (B and C) Total cells and eosinophils contained in 1 ml of BALF. (D and E) Tissue inflammation and goblet cell metaplasia as assessed on H&E- and PAS-stained tissue sections. Micrographs of representative T cell recipients and controls are shown in D; inflammation and PAS scores are shown in E for all mice. Original magnification: ×100 (H&E); ×400 (PAS). All group data of methacholine measurements are presented as mean ± SEM. Total cell and eosinophil counts in BALF are presented for individual mice, with horizontal bars indicating group medians. Inflammation scores and PAS⁺ cells are represented by box and whisker plots, with horizontal bars representing medians and whisker ends indicating minimal and maximal values. Cytokine measurements and PCR results are presented as group mean ± SD.