Myofibroblasts and Subepithelial Fibrosis in Bronchial Asthma

Abstract

A thickened bronchial epithelial basement membrane has long been regarded as a histopathologic characteristic of bronchial asthma. As we had previously demonstrated that this phenomenon is due to the deposition of interstitial collagens and fibronectin, we have now sought to determine the nature of the cell responsible for this process by studying endobronchial biopsies from eight normal and seven asthmatic volunteers by immunohistochemistry and electron microscopy. Biopsies were stained with PR 2D3, a monoclonal antibody to myofibroblasts of the pericrypt sheath of the colon and a monoclonal antibody to alpha-smooth muscle actin. The thickness of the subepithelial collagen and the organelle content of the cells therein were determined by electron microscopy.The subepithelial collagen thickness in the normal subjects ranged from 2.16 to 6.26 µm, while that in the asthmatic subjects ranged from 3.75 to 11.1 µm (Mann-Whitney test; P = 0.05). Elongated cells in the collagen layer were identified by staining ...