PATHOLOGICAL-CHANGES ACCORDING TO THE SEVERITY OF ASTHMA

Background There have been many studies concerning pathological change s in bronchial mucosa from asthmatics; however, few studies has been c arried out to evaluate pathological changes according to the severity of asthma. Objective This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histological abn ormalities in asthmatics according to the severity of asthma. Methods Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural ex aminations were performed in 13 asthmatics and 11 (BAL) or four (biops ies) nonasthmatic controls. The proportions of epithelial cells and eo sinophils in BALF were significantly increased in asthmatics and showe d significant correlations with PC20Meth which reflects bronchial hype rresponsiveness. Light microscopic examination revealed loss of epithe lium, inflammatory cell infiltrations and thickening of the basement m embrane which also showed significant correlation with PC20Meth. Hyper trophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the s everity of asthma. Ultrastructural examination revealed that basement membrane thickening on light microscopic examination is due to the inc reased subepithelial collagen deposition with normal thickeness of bas al lamina. Conclusion These data suggest that loss of epithelial cells , infiltration of inflammatory cells, especially eosinophils, and incr eased deposition of subepithelial collagen play major roles in determi ning the severity of asthma and non-specific bronchial hyperresponsive ness.