Immunocytochemical localization of laminin in hamster tracheal epithelial cell cultures

EM examination of 28 day cultures of enzymatically dissociated hamster tracheal epithelial (HTE) cells grown on collagen coated millipore filters reveals that fragments of basal lamina may be present at the basal plasmalemma. Since the basal lamina consists of several major components including type IV collagen, heparan sulfate proteoglycans, entactin/nidogen, and laminin, questions naturally arise concerning the presence of such a structure in this cell culture system. When immunocytochemical procedures utilizing anti-laminin antibody and PAP techniques are carried out with paraffin sections of HTE culture at 1,2,3, and 4 weeks in vitro, LM analysis reveals that a thin, dense line of reaction product is present between the basal surface of the HTE cells and the underlying collagen substrate. Immunoblotting evaluation carried out with supernatants of 7d HTE cell homogenates and HTE cell conditioned media also indicate that laminin is being produced by the tracheal cells. Thus, the presence of basal lamina-like fragments, the immunocytochemical localization of laminin, and immunoblot identification of laminin in hamster tracheal epithelial cell cultures, suggest that, although basal lamina components may be produced by HTE cells, at the time points tested, they are not yet being organized into a complete basal lamina.