DNA ploidy and proliferative activity of human pulmonary epithelium

DNA ploidy and distribution has been determined in normal and abnormal bronchial, bronchiolar and alveolar epithelium from 22 patients, aged between 0 and 85 years, 9 of whom had received chemotherapy for malignant disease. The DNA ploidy was diploid in all the specimens examined. The S + G2/M fraction was significantly greater in diseased than normal bronchial trees. In the bronchial epithelium, mean values ± the standard deviation (SD) were 5.5 + 2.2% vs 1.1±0.6%, in bronchiolar epithelium 4.6 ± 1.6% vs 1.0 ± 0.9% and in alveolar epithelium 4.6 ± 1.6% vs 0.8 ± 0.5%. The highest S + G2/M value of 8.9% was obtained from inflamed bronchial epithelium. Polyploid cells up to the octaploid range occurred infrequently but their incidence was slightly increased to between 0.16% and 0.9% in diseased lungs and in patients who had received chemotherapeutic drugs. It was concluded that (1) non-cancerous pulmonary epithelium is diploid, that (2) pulmonary epithelium shows steady-state renewal at all ages and polyploid cells are rare under normal conditions and that (3) the S + G2/M fraction increases up to approximately 10% in reactive proliferative states.