Stat3-mut mice have impaired IL-17A production that can be restored in Stat3-mut/PD-1 KO (DM) mice. (A and B) IFN-γ and IL-17A expression by CD4⁺CD44⁺ draining LN cells from WT, Stat3-mut, PD-1 KO, and DM mice was analyzed 1 wk after OVA/CFA immunization. (C) PD-L1 expression on CD4⁺CD44⁻ T cells after 24 h of stimulation with IL-6. (D) Socs3 mRNA levels in CD4⁺CD44⁻ T cells before and after stimulation with IL-6 for 1 h. (E) Fungal load in the tongues and the percentage of CD4⁺CD44⁺IL-17A⁺ cells in cervical LN in Candida-infected mice was determined at d 3 postinfection (pi). One-way ANOVA was performed (B–E). *, P < 0.05; **, P < 0.01. Graphs show means ± SEM. (A-D) WT, n = 5; hyper-IgE syndrome, n = 3; DM, n = 3; PD-1 KO, n = 2. (E) Data were combined from three independent experiments, n = 5–14 mice/group.