Fig. 2

YKL-40 was expression in lung tissues and localized within macrophages and neutrophils. Very faint staining for YKL-40 was observed in the non-smokers (a); In the smokers without COPD, there were more YKL-40 positive cells in the lung parenchyma (b); Smokers with COPD had considerably more YKL-40 positive cells staining in the lung parenchyma (expressed as a percentage of total cells) (c); No immunostaining was observed in control isotype IgG-treated tissue sections (d); Quantification of YKL-40 expression in lung tissues (e); Confocal microscopy showed localization of YKL-40 (green fluorescence) within CD68 or CD45 positive cells (red fluorescence) of the tissue sections (f-i and j-m, respectively). (all images are × 400 magnification). Horizontal bars represent median values