To examine the nature and the degree of leukocyte infiltration and to determine the state of activation of cells in bronchial mucosa of subjects with chronic bronchitis, bronchoscopy was performed in 10 subjects with a history of cigarette smoking and chronic sputum production and in six normal nonsmoking control subjects. Lobar bronchial biopsies were examined using histochemical and immunohistochemical techniques. Subjects with chronic bronchitis had an increased number of total leukocytes (CD45 positive cells), both in the epithelium and in the lamina propria, than did the control subjects (p< 0.05), whereas the numbers of neutrophils, eosinophils, and mast cells were similar in the two groups. There was a significant increase in the numbers of macrophages (p< 0.01) and of T-Iymphocytes (CD3 positive cells)(p< 0.05) in the lamina propria of chronic bronchitics, whereas the relative proportions of CD4 and CD8 positive cells were similar in the bronchitics and the control subjects. Subjects with chronic bronchitis also had an increased expression of markers of lymphocyte activation, le, an increased number of interleukin-2 receptor positive cells (CD25 positive cells)(p< 0.05) and an increased number of very late activation antigen (VLA-1) positive cells (p< 0.05). In conclusion, the present study provides evidence for mononuclear cell infiltration and for T-cell activation in bronchial mucosa of subjects with chronic bronchitis, supporting the involvement of these cells in the pathogenesis of the disease.

Conventionally, chronic bronchitis has been defined in terms of symptoms, particularly as related to chronic sputum production (1). This" symptomatic approach" has always been unsatisfactory because it has never invoked a disease mechanism (2). A" pathologic approach" could provide a better understanding of the cellular mechanisms involved in the pathogenesis of the disease. Descriptions of the pathologic features of chronic bronchitis have been focused mainly on mucous gland hypertrophy (3-7) since this was considered the morphologic basis of the disease. More recent reports have suggested a pathogenetic role for airway inflammation in subjects with chronic bronchitis (8-10), but a precise characterization of the inflammatory cells infiltrating the airway mucosa was not attempted. In lung specimens obtained surgically in smokers with carcinoma, Lamb and Lumsden (11) found an increased number of epithelial mast cells compared with that in control lungs. A detailed study on bronchoalveolar lavage in subjects with chronic bronchitis has shown that the principal cellular change is an increased number of neutrophils (12); however, lavage findings may not necessarily reflect the pathology of airway mucosa (13). Toexamine the nature and the degree of leukocyte infiltration and to determine the state of activation of