XCR1 ⁺ DC are critical for the accumulation of SI CD8 ⁺ effector cells. (A) Experiment setup in which naïve P14 cells were transferred into congenically distinct recipients (WT or XCR1-DTR) prior to LCMV-Arm infection. Both groups were treated with DT from D4–D7 of infection and sacrificed on D8 for analysis. (B) Representative flow cytometry staining of DT-mediated XCR1⁺ cell depletion (LP) pregated on CD45⁺ MHCII⁺ CD11c⁺. (C) Quantification of XCR1⁺ cDC1 frequency. (D) Representative confocal microscopy of murine SI D8 after infection. Stain is indicated in the panel. (E) Quantification of P14 absolute number per villi. Data are representative of two independent experiments. (F) Quantificaton of absolute number of IEL P14 T cells. (G) Representative plot of CD69 and CD103 expression in IEL P14 T cells (left) and frequency quantification (right). (H) Quantification of P14 T cell location across crypt-villi axis. The numbers shown indicate cell counts. (I) Representative histogram of CD127 gMFI (left) and quantification (right) of gMFI in spleen and IEL P14 T cells. (J) Absolute number of P14 T cells isolated from spleen, mLN, and kidney (left) and quantification of TE (KLRG1⁺ CD127⁻) and MP (KLRG1⁻ CD127⁺) populations (right). (K) Experiment setup in which naïve P14 T cells are transferred into recipients (WT or XCR1-DTR) prior to LCMV-Arm infection. Both groups were treated with DT (every 3 days) from D21–D35 of infection and sacrificed on D36 (left). Quantification of P14 T cell number (bottom) and subset frequency (right). P14 T cells gated on CD8α (IV⁻) on all tissue except the spleen. P values are shown. Data are pooled from at least two independent experiments, (A) n = 8 (WT) and n = 7 (XCR1-DTR), (K) n = 15 (WT), and n = 15 (XCR1-DTR). Two-way ANOVA (C and I–K) and unpaired t test (E–G and K).