Glycoconjugate expression in follicle-associated epithelium (FAE) coveringthe nasal-associated lymphoid tissue (NALT) in specific pathogen-free and conventional rats

We examined lectin-histochemically the glycoconjugate expression in the fol licle-associated epithelium (FAE) covering the nasal-associated lymphoid ti ssue (NALT) in the rat under specific pathogen-free (SPF) and conventional (CV) conditions and compared the results for SPF and CV rats as well as for membranous (M) cells and adjacent ciliated respiratory epithelial (CRE) ce lls in FAE. N-acetylgalactosamine-specific lectins, Dolichos biflorus (DBA) , Helix pomatia (HPA), Glycine max (SBA) and Vicia villosa (VVA), and alpha -L-fucose-specific lectin, Ulex europaeus (UEA-I), preferentially bound to M cells mainly in the luminal surface compared with CRE cells in SPF rats, whereas DBA and UEA-I showed signs of preferential binding to the apical an d basolateral cytoplasm as well as to the luminal surface of M cells in CV rats. In addition, HPA, SEA and VVA more frequently and extensively labeled M cells than CRE cells in CV rats with the same subcellular staining patte rn as DBA and UEA-I. On the whole, the changes in lectin binding frequency and strength were more prominent in M cells than in CRE cells in both SPF a nd CV rats. The present results indicate that DBA and UEA-I are useful as m arkers of M cells in NALT. Furthermore, the pattern of expression of carboh ydrate residues recognized by such lectins in SPF and CV rats suggests that M cells are highly sensitive to environmental changes.