Ultrastructural heterogeneity of the alveolar macrophages from tobacco smokers with chronic bronchitis.

Alveolar macrophages recovered by bronchoalveolar lavage from 14 heavy smokers with chronic bronchitis were assessed. Ultrastructural examination revealed marked cellular heterogeneity. Three subpopulations of alveolar macrophages were readily identifiable. These have been termed "young," "mature," and "degrading," reflecting their ultrastructural features. In addition, a majority of the cells were found to be positive by TUNEL staining, indicating DNA damage, but a very small percentage tested positive for Caspase-3, suggesting that apoptosis might not account for the DNA damage in at least some of these cells. A small percentage of proliferating cells were noted.