Quantitative Studies of Human Lung Airspace Wall in Relation to Collagen and Elastin Content

Biochemical determinations of the collagen and elastin content in 50 mm³ samples of human lung are presented in relation to morphometric measurements of lung structure, as the amount of alveolar wall surface area per unit volume (A WUV), on adjacent slices. There were no differences in A WUV values, collagen content (determined as hydroxyproline) or elastin content (determined as isodesmosine) between upper and lower lobes within a single lung. In a study of 102 samples from 9 smokers lungs with no evidence of macro- or microscopic emphysema (as estimated by A WUV measurement), there was a negative correlation between A WUV and the amounts of collagen or elastin per unit volume of inflated lung. The correlation was stronger when collagen and elastin content were expressed per unit area of alveolar wall. The negative correlation is interpreted as representing either the anatomical variation within the complex hierarchy of normal lung structure or possibly low levels of fibrosis in response to cigarette smoking.