Depletion of LC reduces TLR7-induced CD8+ T-cell expansion in vivo. Lang-DTR mice or Batf3^−/− mice were immunized in the footpad with 20 μg of the OVA-TLR7a conjugate. Lang-DTR mice were left untreated (no DT) or treated with 1μg DT injected intraperitoneally 24 hours before immunization (+DT). On day 6 after immunization, blood obtained from the tail vein and cell suspensions from the popliteal LN were stained for OVA-specific CD8⁺ T cells using peptide loaded H-2Kb tetramers as before. (A) Representative dot plots (showing live, CD8+, B220- events) of tetramer staining from the peripheral blood from the indicated hosts. (B) Total number of tetramer+CD8+ T cells in the draining popliteal LN from the indicated hosts. Panels A and B are representative of 3 independent experiments. Statistical significance (Student t test), to the degree indicated by the asterisks (see “Statistical analyses”), was observed between the DT treated Lang-DTR mice and both nonDT treated controls and BatF3^−/− hosts. (C) Normalized data from 2 independent experiments, using 3-7 mice per group per experiment. The number of tetramer+ cells in individual mice was divided by the average number of tetramer+CD8+ cells derived from the WT (B6 or nonDT treated Lang-DTR) mice in the given experiment. This percent of WT control was then plotted for both strains of genetically modified mice as well as for the WT mice to indicate the variability in the responses across strains and across experiments. Statistical significance (Student t test) was observed between the DT treated Lang-DTR and both non-DT–treated controls and Batf3^−/− hosts.