Figure 7.

Pulmonary pDC– and CD8α⁺ DC–mediated rescue of IAV-specific CD8 T cell responses from aDC-depleted mice requires IL-15 trans-presentation. Groups of BALB/c mice were infected with a sublethal dose of IAV with or without aDC depletion as in Fig. 1. On day 3 p.i., groups of aDC-depleted mice were reconstituted i.n. with 2.5 × 10⁴ purified pulmonary pDCs (light gray bars) or CD8α⁺ DCs (dark gray bars) that were left untreated or blocked in vitro with (A) anti–IL-15Rα antibody or (B) anti–IL-15 antibody before adoptive transfer. On day 6 p.i., the number of pulmonary antigen-specific CD8 T cells was enumerated by tetramer staining (left) or ICS for IFN-γ (right). Data are pooled from three separate experiments and represent means ± SEM (n = 9–12 mice/group). (C) Groups of C57BL/6 mice were infected with a sublethal dose of IAV and aDCs depleted at 48 h p.i. (black bars), whereas controls remained undepleted (white bars). On day 3 p.i., groups of aDC-depleted mice were then reconstituted i.n. with 2.5 × 10⁴ purified pulmonary pDCs (light gray bars) or CD8α⁺ DCs (dark gray bars) that were purified from IAV-infected C57BL/6 IL-15^−/− (KO) or wild-type IL-15^+/+ donors. On day 7 p.i., the number of pulmonary IAV-specific CD8 T cells was enumerated by tetramer staining (left) or ICS for IFN-γ (right). Data are pooled from two separate experiments and represent means ± SEM (n = 6–7 mice/group). *, P ≤ 0.05 relative to undepleted control group.