Figure 2. Lung-draining LN Trm cells mediate local protective immunity.

Mice were seeded with 10⁴ naive or 10⁵ 3M P14 cells and IN infected with PR8-GP33 virus. At 50 days post-infection, frequency of 1M or 4M P14s were measured in the peripheral blood (A). At 100 days post-infection, mLNs were harvested and the numbers of total (B) and CD103⁺ CD69⁺ (C) P14s were determined. Representative of three independent experiments, n = 4–5 mice/group. Error bars represent mean ± SD, *p<0.05, **p<0.01, Students t-test in (A–C). LCMV challenge (D,E). Naïve, 1M, or 4M mice were infected with LCMV-Armstrong (2.0 × 10⁵ PFU/mouse i.p.); 72 hr post LCMV challenge, mLN (D) and SP (E) were harvested and individually evaluated for LCMV titers by plaque assay. FTY720 treatment impact on LCMV challenge (F). Naïve, 1M, or 4M mice were infected with LCMV-Armstrong (2.0 × 10⁵ PFU/mouse i.p.) and treated with vehicle or FTY720 daily for 72 hr. 72 hr post LCMV challenge, mLN (F) were harvested and individually evaluated for LCMV titers by plaque assay. Dotted line denotes limit of detection. One representative of 2–3 independent experiments is shown, n = 3–5 mice/group. Error bars represent mean ± SEM (G) or mean ± SD (H). NS = not significant, *p<0.05, one-way ANOVA.