Figure 4.

Intestinal CD8 T cell responses are enhanced by type I IFNs and are essential for barrier leakage during chronic LCMV Cl13 infection. See also Fig. S4. (A–H) C57BL/6 mice were infected with LCMV Cl13 or left uninfected (Un) and injected with isotype (IgG1, red) or anti-IFNAR-1 Ab (αIFNAR, white) i.p. (A, B, and D–H) FACS analysis of the small intestinal IEL or LPL compartments was done on day 9 p.i. Shown are frequencies and numbers of D^bGP_33–41⁺ CD8 T cells (A), as well as PD1 mean fluorescence intensity (MFI; B), frequency of KLRG1⁺ (D), and frequencies and numbers of Tim3^loTCF-1^hi or TCF-1^lo, within D^bGP_33-41⁺ CD8 T cells (E), and their corresponding representative FACS plots. (C) Viral RNA in ileum was quantified by quantitative PCR. (F–H) Frequencies, numbers (F–H), and representative FACS plots (F), as well as IFN-γ mean fluorescence intensity (G) of LPL CD8 T cells upon 5 h of ex vivo PMA/ionomycin stimulation (F and G) or with GP_33–41, GP_276–286, and NP_396–404 peptides (H). (I–K) C57BL/6 mice were infected with LCMV Cl13 or left uninfected (Un) and injected with isotype (IgG2a) or CD8-depleting Abs (αCD8) i.p. In vivo intestinal permeability to FD4 (I), as well as levels of viral RNA (J) and Ifnb (K) in the small intestine, was determined on day 9 p.i. Averages ± SEM are shown (A–K). Data are pooled from two (A–E, J, and K) or three (I) or representative of three (F and G) or two (H) independent experimental repeats. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; Mann–Whitney t test (A–E, G, H, J, and K) or Kruskal-Wallis with Dunn’s multiple comparisons correction (F and I). n.s., not significant.