(A) Flow cytometry histogram (left) and composite graphs (right) of Interferon Regulatory Factor 4 (IRF4) expression in CD44 low naïve, Cryptococcus-specific (Cda2+) Foxp3+ Treg, Cda2+ Foxp3− effector cells collected from the lungs of mice. (B) Histogram of IRF4 expression by lung Treg cells in wildtype and Foxp3-cre IRF4 fl/fl mice 14 days post infection. (C) Cda2+ Th2 cells producing interleukin-5 (IL-5) and/or IL-13 in the lungs of wildtype, Foxp3-cre, and Foxp3-DTR mice 14 days post-infection. (D) IL-5 and IL-13 secreted in lung homogenates from wildtype, Foxp3-cre, and Foxp3-DTR mice 14 days post-infection. (E) Photograph of gross-level pathology of lungs from mice infected 14 days previously (top). Hematoxylin and eosin staining of lung sections from Foxp3-cre mice 14 days post-infection (bottom). Bar = 200 μm. (F) Colony forming units (CFU) in the lungs of wildtype +/− diphtheria toxin (DT), Foxp3-cre IRF4 fl/fl, or Foxp3-DTR + DT. (G) Survival curve of IRF4 fl/fl and Foxp3-cre IRF4 fl/fl infected mice (top). Survival curves of naïve Foxp3-DTR, as well as infected wildtype and Foxp3-DTR mice – all groups treated every other day with 200 ng DT beginning at 5 days post-infection (bottom). Survival curves include 10 mice per group, and P-values calculated by log rank test. Pairwise comparisons were made by Man-Whitney U with Bonferoni adjustments for multiple comparisons. *** = P<0.0005, ** = P<0.005, * = P<0.05, n.s. = non-significant. All data are presented as the mean ± standard error of the mean and represent two independent experiments.