Non-specific bronchial reactivity and ultrastructure of the airway epithelium in patients with sarcoidosis and allergic alveolitis.

There are subgroups of subjects showing increased bronchial responsiveness to histamine among patients with sarcoidosis and with allergic alveolitis (farmer's lung). In these subjects the airway reactivity is comparable with that usually encountered in patients with asthma and in many cases of bronchitis. In many of our patients with hyperreactive sarcoidosis and alveolitis, the increased reactivity was transient, lasting for one to two months during the acute stage of the disease. By electron microscopy we have shown that some of these patients have extensive epithelial damage which could increase epithelial permeability and uncover superficial afferent nerve endings. Indeed, superficial epithelial afferent nerves were found, and it is possible that irritation of these nerve endings causes enhanced bronchoconstriction via the vagal reflex. The transient nature of the hyperreactivity observed in patients with sarcoidosis and alveolitis may indicate that the epithelial changes are readily reversible. The recovery of the epithelium could perhaps be demonstrated by taking serial bronchial biopsies during the course of the disease. Because the electron microscopic specimens represented only a small area of bronchial epithelium, it is difficult to draw any conclusions as to a quantitative relationship between the amount of total epithelial damage and the degree of bronchial reactivity.