Figure 4.

CD8⁺ T_RM cells resided within the peribronchiolar foci in the LI/LP. (A–G) Congenic mice were infected i.n. with x31 and were subjected to parabiotic surgery 18–22 d later. Mice were analyzed at day 14 after the surgery (day 32–36 PI). (A) Representative hematoxylin and eosin (H&E)–stained images of peribronchiolar foci (left) and pan-cytokeratin–expressing cell aggregates in the indicated section of the peribronchiolar foci (right). (B) Mean areas of peribronchiolar foci per sections. (C) Representative peribronchiolar foci in the lung stained with Masson’s trichrome at day 30 PI. (D) Distributions of host (CD90.1⁺) and partner (CD90.2⁺) CD8⁺ T cells inside or outside of peribronchiolar foci. Pan-cytokeratin, green; CD90.1 or CD90.2, red; CD8, blue. Binary images of CD90.1⁺CD8⁺ or CD90.2⁺CD8⁺ cells were generated by using ImageJ software (right). Similar distributions of host and partner cells were also observed in the CD90.2⁺ parabionts. Line-shaped lymph vessels stained by anti-CD90 isoform antibodies were excluded (Kretschmer et al., 2013). Arrowheads indicate host (left) or partner (right) CD8⁺ T cells in the unaffected area. (E) Numbers of host and partner CD8⁺ T cells inside or outside of peribronchiolar foci. (F) Distributions of CD103⁺ host-derived T cells (Thy1⁺) inside or outside of peribronchiolar foci. Pan-cytokeratin, green; CD103, red; CD90.1, blue. (G) Numbers of CD103⁺CD90.1⁺ cells, and ratios of CD103⁺ cells among CD90.1⁺ cells inside or outside of peribronchiolar foci. Data are representative of two independent experiments (mean and SEM of six slides from at least four to five mice per group). (B, E, and G) **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 by Student’s t test. Bars, 200 µm.