THE DISTRIBUTION OF ADHESIVE MECHANISMS IN THE NORMAL BRONCHIAL EPITHELIUM

The integrity of the bronchial epithelium is dependent on various adhe sion mechanisms that serve to hold the composite structure of the epit helium together and anchor it to the underlying basement membrane. Usi ng immuno-histochemistry we wanted to map out a number of these juncti onal and non-junctional adhesion mechanism in the normal human bronchi al epithelium. The beta1-associated integrin subunit alpha2 was immuno localized to all of the epithelial intercellular spaces, whilst alpha6 and beta4 were strongly evident at the basal cell layer basement memb rane junction. The alpha1 and alpha5 integrin subunits were not detect ed anywhere in the epithelium. Monoclonal antibodies (MoAbs) to tight junction polypeptides and the E-cadherin, liver cell adhesion molecule (LCAM), immunolocalized to the apicolateral portions of the intercell ular junctions between all neighbouring columnar cells, with LCAM exte nding further along the lateral cell membrane. Desmosomal protein (dp) 1 and 2 MoAbs gave a punctate pattern between all of the suprabasal c ells, and exhibited the greatest intensity of staining at the junction between the columnar and basal cell layers. In conclusion, there is a n organized distribution of adhesive mechanisms within the normal huma n bronchial epithelium, which may be targeted by the various insults w hich lead to epithelial shedding.