Increased T cell responses to <i>Toxoplasma</i> antigen and crude commensal antigen in <i>Ahr</i>^<i>-/-</i> mice following infection.

<p>Wild type or <i>Ahr</i>^<i>-/-</i> mice were orally infected with 100 <i>T</i>. <i>gondii</i> cysts for 7 days. <b>(A, B)</b> Splenocytes were stimulated with the indicated antigen preparations for 5 hours and then incubated overnight with brefeldin A. The cells were stained to assay IFN-γ expression by CD4⁺ T cells. The graph shows pooled data from 3 independent experiments. <b>(C)</b> Parasite burdens in the terminal ileum were assayed by RT-PCR. Results are pooled from 2 separate experiments.</p

Treg phenotype and IL-10 production in orally infected <i>Ahr</i>^<i>-/-</i> mice.

<p><i>Ahr</i>^<i>-/-</i> mice or wild type controls were infected orally with 20 Me49 cysts for 9 days. Results are pooled from 2–3 separate experiments. <b>(A)</b> Frequency of Tregs in the indicated tissues of wild type or <i>Ahr</i>^<i>-/-</i> mice. In the lamina propria, the plots shown are gated on live CD45⁺CD3⁺CD4⁺ cells, and Tregs were gated as live CD45⁺CD3⁺CD4⁺FoxP3⁺ cells. For the mesenteric lymph node and spleen, the plots shown are gated on CD3⁺CD4⁺ cells, and Tregs were gated as CD3⁺CD4⁺FoxP3⁺ cells. <b>(B)</b> Expression of T-bet, CXCR3, and Ki67 on Tregs in the spleens of wild type or <i>Ahr</i>^<i>-/-</i> mice. The plots are gated on CD3⁺CD4⁺FoxP3⁺ cells. <b>(C)</b> IL-10 secretion by cells isolated from the lamina propria or the spleen following restimulation with soluble <i>Toxoplasma</i> antigen. Results are pooled from 2 separate experiments with a total of 5–7 mice per group.</p

<i>Ahr</i>^<i>-/-</i> mice exhibit increased T cell activation following infection.

<p>Wild type or <i>Ahr</i>^<i>-/-</i> mice were orally infected with <i>T</i>. <i>gondii</i> for 9 days. <b>(A)</b> Group 3 ILC frequency in the lamina propria of wild type or <i>Ahr</i>^<i>-/-</i> mice following infection. The plots on the left are gated on live CD90.2⁺CD11c^-B220^- cells. (<b>B)</b> Weight loss was monitored at various days post-infection. Data are pooled from 2 experiments with 6–8 mice per group. <b>(C)</b> H&E staining of small intestinal tissue sections. <b>(D)</b> H&E staining of small intestinal tissue from an infected <i>Ahr</i>^<i>-/-</i> mouse. The Peyer’s patch exhibits severe lymphocytolysis (*) and the lamina propria of adjacent villi is expanded by primarily lymphocytes and plasma cells (➜). <b>(E)</b> A higher magnification image of the section in Fig 2C shows that the Peyer’s patch exhibits severe lymphocytolysis characterized by pyknosis and other cellular debris. <b>(F)</b> H&E staining of small intestinal tissue from an infected <i>Ahr</i>^<i>-/-</i> mouse shows crypt loss (*) and multifocal necrotic enterocytes (➜). The lamina propria of the villi is expanded by lymphocytes and plasma cells (❋). <b>(G)</b> Expression of T-bet and Ki67 by FoxP3^- CD4⁺ T cells in the mesenteric lymph nodes of infected mice. Results are pooled from 3 separate experiments. <b>(H)</b> Cytokine production by CD4⁺ T cells following stimulation with PMA/ionomycin. Data are pooled from 2 experiments.</p