Atypical differentiation of bronchiolar epithelial cells following experimental pneumonia

In the bronchiolar and alveolar epithelial responses to experimentally induced organizing pneumonia in the rat evoked by Streptococcus pneumoniae type 25, the appearance of lamellar body-containing bronchiolar cells is reported. Such cells, which are interspersed among proliferating type 2 pneumocytes in the form of intraalveolar and bronchiolar buds, also stain immunohistochemically with antisera to alveolyn, a surfactant-associated protein. We believe this phenomenon supports an hypothesis that in response to specific stimuli, proliferation of a common precursor cell of both the bronchiolar Clara cell and the type 2 pneumocyte occurs, with varying expression of a latent or precursor capacity for surfactant secretion.