medLN TRM durably increase regional memory. P14 cells were transferred to naive mice, followed by PR8-gp33 influenza virus infection i.n. (A and B) Dynamics of CD103 and ITGβ7 expression among P14 cells isolated from medLN and lung. Numbers in A represent fold difference between lung and medLN. *, P < 0.05; ***, P < 0.001 as determined by an unpaired Student’s t test. (C) Comparison of medLN size between naive mice and mice infected 120 d earlier with PR8-gp33. (D and E) Enumeration of ITGβ7+ CD103+ P14 cells isolated from the lung and medLN. Data representative of at least four mice per time point. Error bars represent mean ± SEM. (F and G) PD-1 and granzyme B expression on memory P14 cells isolated from the indicated tissues 85 d after infection, as determined by flow cytometry. Similar results were obtained from mice analyzed 30 d earlier. (H) As in F, percentage of P14 cells that produce both IFNγ and TNFα after 4-h ex vivo peptide restimulation. Bars represent mean ± SEM. (I) IF imaging of the medLN 120 d after PR8-gp33 infection. Closed arrowheads indicate bright Thy1.1 staining; open arrowheads indicate less intense Thy1.1 staining.
