Distribution of mast cells and eosinophils in nasal polyps from atopic and nonatopic subjects: a morphometric study.

The pathogenetic mechanism of nasal polyps remains unknown, although polyps seem to be an expression of chronic nasal inflammation of both allergic and nonallergic origin. The goal of our study was to compare the distribution mast cells and eosinophils (cells traditionally associated with allergic inflammation) in nasal polyps from well defined atopic and nonatopic patients, using advanced morphometric analysis system. Nasal polyps were removed during routine nasal polypectomy performed in 17 atopic and 19 nonatopic patients. Parafin sections of nasal polyps were stained with haematoxilin/eosin, chromotrope R2 or toluidine blue, and light microscopy, assisted with computerized picture analysis system, was used to count the number of cells in the superficial and stromal layer of the mucosa. Regardless of the presence or absence of atopy, eosinophils were predominant cells in the polyps, and both eosinophils and mast cells were more abundant in the superficial layer than in the stromal layer of the mucosa. The density of eosinophils in both layers and mast cells in the stromal layer was similar in atopic and nonatopic patients. Only the density of mast cells in the superficial layer of the mucosa was slightly higher (p < 0.005 in atopic compared to nonatopic patients): In both groups of patients a significant correlation between the number of mast cells and eosinophils in the superficial layer of the polyp mucosa was found (r = 0.84; p < 0.001). Our study demonstrates that eosinophils and mast cells are abundant in nasal polyps from both atopic and nonatopic patients and that mast cells seem to be more superficially distributed in atopic compared to nonatopic patients.