Cover: Histochemical localization of hyaluronan (HA) after bleomycin injury. (a) Control section of normal, uninjured rat lung stained using biotinylated HA binding region of aggrecan (bHABP) that had previously been preincubated with excess unlabeled HA. The lack of staining confirmed the specificity of the probe for HA. (b) Constitutive expression of HA (brown color) occurred in the subepithelial matrix of bronchioles and around bronchiolar smooth muscle. (c) At 4 d after bleomycin injury, maximal staining for HA was seen in macrophages accumulating in injured areas of the lung (arrows). These changes were not observed in saline-treated animals (data not shown). (d-f ) Colocalization ( f, yellow) of fluorescein isothiocyanate (FITC)-ED-1 to identify rat macrophages (d, green) and Texas Red-bHABP to bind HA (e, red ) indicates that HA is localized to macrophages. Staining for HA in other areas is also noted. The inset in d shows a higher-power image of a macrophage close to the HA staining noted in the subepithelial matrix. Arrows indicate macrophages. The photomicrographs shown are representative of five independent experiments. Original magnification: ×400 for all photomicrographs except the inset in f, which is ×1,000. For more information see article by Savani and colleagues 475.
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