FIG. 1.

(a and b) Identification of dendritic cells on frozen lung tissue sections from normal lung tissue of C57BL/6 mice. Shown are tissue sections stained with anti-CD11c⁺ (N418) at magnifications of ×400 (a) and ×1,000 (b). (c) Hema 3 staining of nonadherent CD11c⁺ lung cells after overnight culture and centrifugation onto glass slides. Cells in the left panel show the homogeneity of the culture, with most cells demonstrating the typical morphology of the immature dendritic cells. All the cells presented large nuclei, abundant cytoplasm, and small cytoplasmic projections (top right panel). In these cultures, there were also cells apparently in the proliferation stage (bottom right panel). The sizes of the cells varied (see Fig. 2, FSC and SSC in the flow cytometric analysis). (d) Adherent CD11c⁺ lung cells were stained using Hema 3 stain after 7 days of culture and adherence on Thermovox coverslips. These cells had elongated morphology with very long cytoplasmic processes and large central nuclei (magnification, ×200). (e) In vitro infection of lung dendritic cells. Lung dendritic cells were infected in vitro at a ratio of 10 bacilli per cell. After overnight infection and centrifugation onto glass slides, cells were stained for acid-fast bacilli (arrows) using Ziehl-Neelsen stain (magnification, ×400).