PD-1 expression on Th2 cells during N brasiliensis infection. Lung (A) and mesenteric lymph nodes (B) of 4get (WT) and 4get/Stat6^−/− (Stat6^−/−) mice were analyzed before or at indicated days after N brasiliensis infection. Dot plots are gated on CD4⁺ cells and show staining for PD-1 or isotype control versus expression of IL-4/eGFP at day 13 after N brasiliensis infection. The graphs show the frequency and absolute number of PD-1⁺ cells among Th2 cells (CD4⁺ IL-4/eGFP⁺ T cells) from WT (●) or Stat6^−/− (○) mice as mean ± SE of 3 individual mice from 2 independent experiments (***P ≤ .001; **P ≤ .01; *P ≤ .05). (C) Effect of anti-PD-L2 mAb treatment during N brasiliensis infection on the Th2 response and PD-1 expression on T cells. Anti-PD-L2–treated or rat IgG-treated mice were analyzed at day 9 after infection. Dot plots are gated on CD4⁺ cells and show staining for PD-1 versus expression of IL-4/eGFP. Bar graphs show the frequency of PD-1⁺ cells among CD4⁺IL-4/eGFP⁺ cells (left) and the frequency of IL-4/eGFP⁺ cells among all CD4⁺ cells (right) as mean ± SE of 4 individual mice from 2 independent experiments (*P ≤ .05).