Airway wall remodeling after cessation of exposure to isocyanates in sensitized asthmatic subjects.

To determine whether the cessation of exposure to isocyanates is associated with structural changes of the airway wall in sensitized subjects, we studied bronchial biopsies from 10 subjects with occupational asthma induced by toluene diisocyanate (TDI). Bronchial challenges with TDI and methacholine were performed and biopsies were taken on two occasions, at diagnosis and 6 to 21 mo after cessation of exposure to TDI. After bronchoscopy, biopsies were formalin-fixed or snap-frozen in liquid nitrogen and then processed for a quantitative histochemical and immunohistochemical analysis. After cessation of exposure, we observed a significant decrease of the sensitivity to TDI (p < 0.05), of the thickness of subepithelial fibrosis (p < 0.007), and of the numbers of subepithelial fibroblasts (p < 0.05), mast cells (p < 0.02), and lymphocytes (p < 0.03) as compared with values at diagnosis. By contrast, the nonspecific bronchial hyperresponsiveness and the numbers of macrophages and eosinophils did not change. I...