Cytological and cytochemical alterations in the respiratory tract of mice after exposure to cigarette smoke, influenza virus, and both.

Abstract

Correlated histological, cytological, and cytochemical studies of sequential changes in the respiratory tract of mice after exposure to the inhalation of cigarette smoke, influenza virus, and a combination of both disclosed atypical proliferative lesions accompanied by moderate intracellular DNA, RNA, and protein increase. In mice exposed to influenza virus alone, or in combination with cigarette smoke, a striking increase in abnormal intracellular RNA agglomerations, associated with absence of mitosis and cell destruction, preceded the atypical proliferations of other cells in the respiratory tract. The frequency of atypical proliferative changes was lowest after inhalation of cigarette smoke, higher after influenza virus, and a cumulative effect was noted after the combination of virus and cigarette smoke. In the latter group squamous-cell metaplasia and transgression of epithelial cells into lung parenchyma were found more often in males than in females.