CELL-PROLIFERATION IN LUNG FIBROSIS-ASSOCIATED HYPERPLASTIC LESIONS

1 Cell proliferative activity of atypical bronchioloalveolar epithelia in lung fibrosis cases treated with bleomycin (BLM) or radiation was investigated by studying the histochemistry of the argyrophil nucleola r organiser regions (AgNORs) and proliferating cell nuclear antigen (P CNA). 2 Five and 14 autopsy cases of individuals who died of pulmonary fibrosis, caused by BLM treatment and irradiation respectively, were compared with (i) six control subjects who proved to have no apparent fibrosis of the lung at autopsy and (ii) four lung squamous cell carci noma cases. 3 Histopathologically, both the ELM-treated and irradiated cases showed extensive collapse of the lung caused by severe fibrosis , although proliferative epithelial lesions such as atypical bronchiol oalveolar hyperplasia and squamous metaplasia were more prominent in t he former. 4 The mean AgNOR numbers in both atypical hyperplasias and metaplasias, of either BLM or irradiation cases, were significantly hi gher than in control bronchioloalveolar epithelial areas, whereas they were lower than in the lung cancers. Data for PCNA-labelling indices were in line with those for AgNORs. 5 The results indicate that atypic al hyperplastic lesions in the bronchioloalveoli arising during the fi brosing process as induced by BLM, and by irradiation, are highly prol iferative.