DCs sweep the alveolar air space using transepithelial dendrites. (A) Motility of CD11c-EYFP DCs in the alveolus of an OVA-challenged mouse stained with Hoechst. The arrow indicates an extended dendrite. (B) Alveolar motility of a CD11c-EYFP DC in a PBS-treated Actin-CFP mouse. (C) Quantification of dendrite numbers per alveolar DC for PBS- and OVA-challenged lungs. (D) Surface area of alveolar DCs from PBS- and OVA-challenged mice calculated using the isosurface tool in Imaris. (E) Track speed means of alveolar DCs before LPS treatment or after 10 min or 3 h of LPS treatment. (F) Intravital in vivo motility of a CD11c-EYFP DC in the alveolus of an Actin-CFP mouse that is anesthetized, ventilated, and imaged with two-photon microscopy. (B and F) Dotted lines trace the dendrite surface. Bars: (A, B, and F, left) 50 µm; (A and B, right) 20 µm; (F, right) 10 µm. (G) Quantification of intravital in vivo dendrite numbers per alveolar DC for PBS- and OVA-challenged lungs. (H) Mean squared displacements as a function of time for AMs from in vivo lungs corrected for breathing artifacts with type II epithelial cells versus sectioned lungs. (C–E, G, and H) Error bars represent SEM. Images are representative images from >12 mice per group for slice and 4 mice per group for live imaging. Quantification of dendrites, surface area, and track speed means are combined data from three separate experiments.