The expression of intercellular adhesion molecule-1 and the β1-integrins in asthma

Abstract

Expression of intercellular adhesion molecule-1 (ICAM-1) appears to be important to the development of bronchial hyperresponsiveness and eosinophilia in Ascaris sensitized monkeys. Beta1-integrins are expressed on epithelial cells, and may contribute to adherence of epithelial cells to the basement membrane. The aim of this study was to determine whether adhesion receptor expression was altered in human asthmatic branchial epithelium. Using monoclonal antibody staining, we have examined the expression of ICAM-1 and the α1-α6-subunits of the β-integrin family in bronchial mucosal biopsies from 33 asthmatic and 13 nonasthmatic subjects. The epithelium was positive for ICAM-1 in 26 out of 33 asthmatics, although negative in all 13 nonasthmatics. ICAM-1 expression was not associated with bronchial responsiveness or with medication requirements. Beta1-integrin staining showed that α2-, α3- and α6- subunits stained the epithelium in all cases. Alpha, staining was weakly positive in the epithelium in five asthmatics. Alpha, staining was weak in asthmatics and normals. Alpha4 and α6- subunits also stained inflammatory cells. Epithelial upregulation of ICAM-1 is present in asthma. Beta1-integrins with α2-, α3- and α6-subunits appear to be constitutively expressed in bronchial epithelium.