Do bronchial biopsies represent mast cell density in airways? A stereological study

Endobronchial biopsy specimens may not adequately represent inflammatory cell counts throughout the airway wall. The present study aimed to compare mast cell density in biopsies and airway sections using both stereological and nonstereological methods. Post mortem biopsies and adjacent transverse sections were obtained from a mean of five proximal airways per case in 10 subjects who had died of nonrespiratory causes. Tryptase-positive mast cells were measured stereologically in 30-mum sections and nonstereologically in 5-microm sections using an optical disector (cells x mm(-3)) and cell profiles (cells x mm(-2)), respectively. Reference areas included the inner and total airway wall and to 100 microm below the basement membrane. Case means, based on four or more biopsy sites, significantly correlated with those on transverse sections for counts over the inner airway wall only, using both stereological and nonstereological methods. Cells x mm(-3) and cells x mm(-2) were significantly correlated within all reference areas. When endobronchial biopsies are obtained from at least four proximal airways per case, inter-subject comparisons of mean mast cell density in the inner airway wall are as well represented by counts on biopsies as they are on transverse sections. This is the case using either three-dimensional, stereological or two-dimensional, nonstereological methods.