The relationship between large airway and alveolar space inflammation and airway metaplasia

Bronchoscopy and bronchoalveolar lavage (BAL) yield important information about the lower respiratory tract of subjects who have been exposed to asbestos. Evidence of metaplasia is easily detected with random biopsies in large airways and a relationship with smoking status can be found. A significant finding, however, is that inflammatory cells recovered by late BAL aliquots which presumably reflect alveolar space inflammation are also importantly associated with the presence of metaplasia. Asbestos provides an important stimulus for recruitment of inflammatory cells. These cells release oxidants which can be responsible for direct or indirect mutagenesis. Our data suggest that this inflammatory cell recruitment may be an important additional factor predictive of airway metaplasia and perhaps subsequent carcinogenesis.