THE EXPRESSION OF INTERCELLULAR-ADHESION MOLECULE-1 AND THE BETA-1-INTEGRINS IN ASTHMA

Expression of intercellular adhesion molecule-1 (ICAM-1) appears to be important to the development of bronchial hyperresponsiveness and eos inophilia in Ascaris sensitized monkeys. Beta(1)-integrins are express ed 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 b ronchial epithelium. Using monoclonal antibody staining, we have exami ned the expression of ICAM-1 and the alpha(1)-alpha(6)-subunits of the beta(1)-integrin family in bronchial mucosal biopsies from 33 asthmat ic and 13 nonasthmatic subjects. The epithelium was positive for ICAM- 1 in 26 out of 33 asthmatics, although negative in all 13 nonasthmatic s. ICAM-1 expression was not associated with bronchial responsiveness or with medication requirements. Beta(1)-integrin staining showed that alpha(2)-, alpha(3)- and alpha(6)- subunits stained the epithelium in all cases. Alpha, staining was weakly positive in the epithelium in f ive asthmatics. Alpha, staining was weak in asthmatics and normals. Al pha(4) and alpha(6)- subunits also stained inflammatory cells. Epithel ial upregulation of ICAM-1 is present in asthma. Beta(1)-integrins wit h alpha(2)-, alpha(3)- and alpha(6)-subunits appear to be constitutive ly expressed in bronchial epithelium.