Figure 2. Influenza-specific cytotoxicity in vivo depends on TLR7 activation.

Wt (black bars) and TLR7−/− (white bars) mice received two doses (on day 0 and 21) of WIV (25 µg; s.c.), replicative virus (400 HAU; i.p.) or HNE buffer (s.c.). One week later, mice were injected through the orbital vein with a 1∶1 mixture of NP- and OVA-pulsed target cells, differentially labeled with high and low concentrations of CFSE, respectively. NP_366–374 tetramer-positive CD8+ T cells (A) and cytotoxicity expressed as % of killed target cells (B) were measured by tetramer staining and flow cytometric analysis of splenocytes isolated from immunized mice 13 hours after target cell injection. Gating was based on the forward-side scatter pattern and dead cells (7AAD+) were excluded. Finally, gates were set on CD8+tetramer+ cells. Results are representative of 3 independent experiments. Bars represent mean±SEM of 5 mice per group. *p<0.05; Mann-Whitney U-test.