CD8+ T-lymphocytes in peripheral airways of smokers with chronic obstructive pulmonary disease

To investigate whether the inflammatory process in peripheral airways is different in smokers who develop symptoms of chronic bronchitis and chronic airflow limitation and in asymptomatic smokers who do not develop chronic airflow limitation, we examined surgical specimens obtained from 16 smokers undergoing lung resection for localized pulmonary lesions. Nine had symptoms of chronic bronchitis and chronic airflow limitation and seven were asymptomatic with normal lung function. In peripheral airways, immunohistochemical methods were performed to identify neutrophils, macrophages, CD4⁺ and CD8⁺ T-lymphocytes infiltrating the airway wall, and morphometric methods were used to measure the internal perimeter, the airway wall area, and the smooth muscle area. The number of CD8⁺ T-lymphocytes and the smooth muscle area were increased in smokers with symptoms of chronic bronchitis and chronic airflow limitation as compared with asymptomatic smokers with normal lung function, while the number of neutrophils, macrophages, and CD4⁺ T-lymphocytes were similar in the two groups of subjects examined. We concluded that smokers who develop symptoms of chronic bronchitis and chronic airflow limitation have an increased number of CD8⁺ T-lymphocytes and an increased smooth muscle area in the peripheral airways as compared with asymptomatic smokers with normal lung function, supporting the important role of CD8⁺ T-lymphocytes and airway remodeling in the pathogenesis of chronic obstructive pulmonary disease.