Abstract
It has been suggested by some studies of human and animal lungs that the products of pulmonary endocrine cells, particularly gastrin-releasing peptide, might play a role in fibrogenesis, but more recent detailed studies of fibrotic human lungs have failed to confirm this. We have made a detailed quantitative examination of a series of fibrotic human lungs to see if we could determine whether there was any relationship between endocrine cells and fibrosis. Using immunocytochemistry, we investigated the morphology, content, distribution and number of pulmonary endocrine cells in 15 pairs of fibrotic lungs from coal miners, and compared their features with those of equivalent cells in age-matched controls. Proliferation of endocrine cells was seen in the lungs of just two miners, in which it was focal and associated with acute bronchitis and bronchopneumonia. There was no difference between the miners and controls in the appearance (mostly solitary cells), content (predominantly gastrin-releasing peptide and calcitonin), distribution (mainly in small bronchi and bronchioles), or number (4.5 vs 4.1 cells per 10,000 epithelial cells, respectively) of endocrine cells. It seems unlikely that the substances secreted by these cells play any role in stimulating fibrosis in human lungs, but rather that they have a function in the inflammatory response to pulmonary injury.
