Fig. 5.

Polyps show a strong immune infiltration. Lungs were recovered from naive, Mf^neg and Mf^pos gerbils at 70 days p.i. Immune cells were stained in 4 µm thick sections. a–f Immunostainings were performed for leukocytes (CD45), lymphocytes (CD3) and macrophages (CD68). Overview of lungs section from naive (a), Mf^neg (b) and Mf^pos (c) gerbils stained with CD45 (brown). d–f View of a large polyp stained for CD45 (d), CD3 (e) and CD68 (f). Arrows show subpleural inflammatory foci. g Eosinophils were stained with Congo red; arrows indicate eosinophils. h Mast cells were stained with Toluidine blue. In all images, the right quadrant shows a zoom of positive cells. i Quantification of cell concentrations in small polyps (< 150 µm), large polyps (> 150 µm) and subpleural infiltrates. Results are expressed as the mean ± SEM (n = 7 Mf^pos gerbils for CD45, CD3, CD68 and toluidine blue staining and 4 for Congo Red)