Changes in the alveolar connective tissue of the ageing lung. An immunohistochemical study.

The modifications of the extracellular matrix (ExM) components in the alveolar parenchyma of elderly subjects were investigated using a panel of polyclonal antibodies. The elastic fibers showed a notable decrease along the alveolar walls while type III collagen increased when compared with that of non-elderly controls. No variations of these components were detectable in the alveolar ducts or in the respiratory bronchioli. An increase in the thickness of the alveolar basement membranes was detected in some of the subjects when antibodies against type IV collagen and laminin were used, while antibodies to fibronectin and type V collagen did not reveal any modifications compared with the controls. The modifications revealed in the lungs of the elderly can be related to the alterations of the elastic recoil and pulmonary compliance observed in these subjects.