FIGURE 1.

Detection of the human- and avian-type flu receptors in lung sections and organotypic bronchoepithelium from patients with chronic obstructive pulmonary disease (COPD) and controls. Human lung sections (COPD n = 5, control n = 5) and primary human bronchial epithelial cells (phBECs) from patients with COPD (n = 4) and controls (n = 3) were stained with Sambucus Nigra lectin (SNA) that specifically binds to sialic acids bound to galactose by the α2,6 linkage, SAα2,6Gal, the human-type flu receptor, and a monoclonal antibody (clone HYB4) that specifically binds to SAα2,3Gal, the avian-type flu receptor. (A) Detection of human-type flu receptor (green) in co-staining with antibodies directed toward acetylated tubulin (acTub), mucin 5AC (MUC5AC), or club cell-specific protein CC10 (red), for the identification of ciliated, goblet, or club cells, respectively, in formalin-fixed, paraffin-embedded human lung sections. The example shown is from a COPD lung explant. (B) Detection of human-type flu receptor (green) and avian-type flu receptor (red) in phBECs from COPD and control on days 0, 14, and 28 after airlift. (C) Quantification of the human- and avian-type flu receptors in phBECs on days 0, 14, and 28 after airlift. Panel (A) shows representative images for n = 5 (COPD) and n = 5 (control lung sections). Panel (B) shows representative images for n = 3 (control phBECs; here second control, see Table 1) and n = 4 (COPD phBECs; here GOLD stage III-derived phBECs); quantification of those data is given in panel (C). For panel (C), statistical analysis was performed using an unpaired, two-sided Mann–Whitney U test, but with a cutoff value of p < 0.05, no statistically significant differences were observed.