Connective Tissue of the Lung

Emphysema and pulmonary fibrosis are important chronic lung diseases which are increasing in prevalence. There is evidence that they are two of a limited number of responses which the lung can make to environmental agents. The recent demonstration of an association between deficiency of circulating antienzymes for proteases and emphysema has stimulated hope that first, a mechanism has been found for emphysema and second, that a chemical label may have been found to identify susceptible subjects. From animal model studies has come evidence that the instillation or aerosol deposition of proteases such as papain into alveoli produces a lesion which resembles human centrilobular emphysema. Perhaps the most encouraging news is that a quarter of the papers in this Symposium on Pollution and Lung Biochemistry concern connective tissue, its synthesis, composition and responses to injury. Examination of tissue sections of the lung suggests that the bulk of connective tissue is in