Figure 2.

Cellular sources of cathepsin B. Cellular sources of cathepsin B were analyzed by immunofluorescence microscopy using staining with a cathepsin B-specific antibody. The cell types of cathepsin B-expressing cells were determined by antibodies against specific surface antigens. A: Immunofluorescence staining of cathepsin B (red) and specific cell surface antigens (blue) in tissue from the right ear and draining lymph nodes of sensitized mice 24 h after TNCB challenge allowed the identification of cathepsin B-expressing immune cells (green represents nuclei). Cells with both antibodies bound appear purple. B: Cells onto which both anti-cathepsin B- and anti-cell surface antigen antibodies bound (purple), were counted. The results are shown as the percentage of all cells expressing the specific cell surface antigen (blue+purple). At the site of inflammation (the right ear) in sensitized mice 24 h after TNCB challenge, CD11c-positive dendritic cells exhibited the highest percentage of cells expressing cathepsin B, while CD49b-positive NK cells expressed cathepsin B most rarely among the immune cell populations (n=4; mean±SEM). C: In draining lymph nodes of sensitized mice 24 h after TNCB challenge, the percentage of cells expressing cathepsin B was higher than that in inflamed ear tissue. Almost 80% of the F4/80-positive macrophages expressed cathepsin B, while only a few cells in the other populations produced cathepsin B (n=4; mean±SEM). D: In cervical lymph nodes of naïve mice, 53% of the CD49b-positive NK cells expressed cathepsin B, while the expression of cathepsin B in F4/80-positive macrophages and CD11c-positive dendritic cells was comparatively low (n=2 mean±SEM).