Normal Newborn and Adult Human Lung Collagen — Analysis of Types

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Abstract
Previous work has shown in experimental animals that lung contains extractable collagen of types I and II and possibly III and IV. The current studies describe the types of collagen which are found in normal newborn and adult human lung. Autopsy lung specimens were dissected into tissue which was cartilage free and tissue which contained cartilage. Pleura was excluded. Extraction of distal lung which did not contain cartilage by using 1.0 M NaCl and 0.5 N acetic acid yielded collagen having the characteristics on acrylamide gel electrophoresis and CM-cellulose chromatography of type I collagen [αl(I)]2α2. Newborn and adult type I lung collagen are similar as compared by amino acid analysis and cyanogen bromide peptide fragment analysis. Furthermore, distal lung type I collagen is very similar, if not identical, to that found in human skin. Human bronchial cartilage collagen is similar to that found in other human cartilages. Type III collagen, [αl(III)]3, can be extracted from human distal lung using pepsin digestion and differential salt precipitation at 1.85 M sodium chloride. This distal lung type III collagen appears identical with that found in human skin. These data support the concept that normal human lung contains collagen of types I, II, and III, identical to that found elsewhere in the body. Current techniques have not revealed a unique lung collagen. This should lead to studies which will investigate the types and ratios of the collagens in diseased human lung.