Mtb-specific CD4 T cells in the lungs of PD-1 KO mice are less differentiated, more parenchymally localized and produce increased amounts of IFN-γ.

<p>(<b>A</b>) Survival of WT and PD-1 KO mice after Mtb infection. Data are representative of at least three independent experiments. (n = 5-6/experiment). (<b>B</b>) IFN-γ levels in the lung homogenates of WT and PD-1 KO mice on day 30 p.i. Data are pooled from three independent experiments (n = 3-4/experiment). (<b>C</b>) PD-1 expression on the parenchymal and intravascular I-A^bESAT-6_4–17 or I-A^bEsxG_46–61–specific CD4 T cells in WT lung on day 30 p.i. (<b>D</b>) Iv-staining of I-A^bESAT-6_4–17–specific CD4 T cells in the lung of WT and PD-1 KO mice on day 30 p.i. Data are pooled from three independent experiments (n = 3-4/experiment). (<b>E</b>) Phenotypic analysis of I-A^bESAT-6_4–17–specific CD4 T cells in WT and PD-1 KO lungs on day 30 p.i. (<b>F</b>) Intracellular IFN-γ staining of lung CD4 T cells in WT and PD-1 KO mice after in vitro stimulation with ESAT-6_1–20 peptide on day 30 p.i. Data are pooled from three independent experiments (n = 3-4/experiment). (<b>G</b>) Direct ex vivo IFN-γ staining for I-A^bESAT-6_4–17–specific CD4 T cells in the lungs of WT and PD-1 KO mice on day 30 p.i. Data are pooled from three independent experiments (n = 3-4/experiment). Cells in (<b>A</b>) and (<b>E</b>) were pooled from n = 3/experiment for FACS analysis. ***, <i>P</i><0.0005; ****, <i>P</i><0.0001.