Figure 6.

OPG in LAM lung lesions. A and B: Reaction with antibodies against OPG in LAM lung nodules in sections of explanted LAM lungs. C: Reactions in cells lining vessels. Original magnifications: ×40 (A); ×400 (B); ×200 (C). The arrow indicates anti-OPG reactivity in alveolar structures (A). Anti-OPG reactivity in LAM cells and alveolar macrophages (B). The arrowhead indicates a vascular structure, whereas the arrow indicates a LAM nodule (C). D: Confocal fluorescence imaging of lung sections. Strong positive reactivity to anti-OPG antibody (Texas Red, red) is localized to the lining of vascular structures, with weaker reactivity in cells throughout the parenchyma. E: CD31 (FITC, green)– and OPG (Texas Red, red)–positive cells are seen in a vascular structure of a LAM lung section. F: Higher magnification of another LAM tissue section revealed cells with reaction to antibodies against both OPG and CD31 within the same vascular endothelial cells (merge, yellow) lining a vessel. G: Reaction with antibodies against OPG and podoplanin (FITC, green) is evident in a LAM lung section, without, however, colocalization of immunoreactivities within the same cell. H: HMB45 (FITC, green)– and OPG (Texas Red, red)–positive cells in a proliferative region of a LAM lung. I: Higher magnification of a tissue section demonstrated positive reactivity to HMB45 and an antibody to OPG within the same cell (merge, yellow), suggesting that LAM cells express OPG. J: Cells immunopositive for OPG (Texas Red, red) line vascular structures in normal lung tissue. K: No reaction to OPG is observed in normal lung alveolar cells, in contrast to the diffuse expression of OPG in LAM lung tissue. L: Control staining of normal human lung using IgG mouse control. The nuclei of cells were counterstained with DAPI (blue). Results were similar in at least three different samples for each pair of antibodies. LAM lung sections are from different patients (D, E, G, and H). Scale bar = 20 μm (D–L).