Fig. 5. OX40 agonism improves TB outcomes and increases CD4 T cell numbers.

a Flow cytometry of CD4 and CD8 T cells from wildtype C57BL/6 lungs at four weeks post-infection. Gated on live CD4^+cCD44⁺ or CD8^+cCD44⁺ cells. P value = 0.00007 calculated with a paired two-tailed t-test, 4 mice per group. b–e Wildtype C57BL/6 mice at four weeks post-infection treated with 100 μg α-OX40 agonist, α-PD-1 blockade, or isotype control antibody injections twice weekly for two weeks. Mice followed for survival or lungs harvested one day after the last antibody treatment for flow cytometry and lung bacterial load. b Curves show survival of α-OX40 or isotype control antibody-treated wildtype or TCRα-/- mice. P value calculated with a two sided Mantel-Cox test, 4-5 mice per group. c Lung bacterial load of α-OX40, α-PD-1, or isotype control antibody-treated mice. One-way ANOVA p = 0.0078; p values shown in figure calculated with post hoc testing adjusted for multiple comparisons. Mice per group: 6 for isotype, 7 for PD-1, and 8 for OX40. d Number of CD4 and CD8 T cells in the lungs of α-OX40, α-PD-1, or isotype control antibody treated mice. Gated on live CD4⁺ CD44⁺ or CD8⁺ CD44⁺ cells. Cell numbers assessed using counting beads. Data representative of two repeat experiments. One-way ANOVA for CD4 T cells p = 0.00002, CD8 T cells p = 0.1023; p values shown in figure calculated with post hoc testing adjusted for multiple comparisons. P value for PD-1 vs OX40 group = 0.00005. Mice per group: 8 for isotype, 7 for PD-1, and 10 for OX40. e Number of Tetramer⁺ CD4 T cells in the lungs of α-OX40, α-PD-1, or isotype control antibody-treated mice. Gated on live CD4⁺ CD44⁺ Tetramer⁺ cells. Tetramer⁺ cells represent either Ag85B or ESAT-6 specificity. Cell numbers assessed using counting beads. One-way ANOVA p = 0.0047, p values shown in figure adjusted for multiple comparisons. Mice per group: 3 for isotype, 3 for PD-1, and Mice per group: 8 for isotype, 7 for PD-1, and 10 for OX40. 4 for OX40. Error bars indicate standard deviation.