MODULATION OF THE GLYCOCONJUGATE EXPRESSION IN THE TRACHEOBRONCHIAL EPITHELIUM DURING SUSTAINED HYPOVITAMINOSIS-A

The aim of this study was to determine the influence of sustained marg inal vitamin A deficiency on the morphology of glycoconjugate expressi on in the tracheobronchial epithelium of guinea pigs. The distribution of oligosaccharide chains was investigated by applying a panel of 24 lectins, Glycosaminoglycans were detected by histochemical techniques. Number as well as morphology of ciliated cells showed no significant alterations in hypovitaminosis A. In contrast, the quantity of goblet cells was constantly decreased. A considerable reduction of secretory granules was also observed in these cells. Cytomembranes of ciliated c ells (especially in the area of ciliar extensions) showed constant alt erations in the patterns of lectin binding in vitamin A-depleted guine a pigs. Our results demonstrate a significant augmentation of accessib ility of fucosyl molecules in proximal domains of glycoconjugates of c iliary membranes, whereas the presence of mannose structures seemed un changed. In distal bronchioli, terminal N-acetylgalactosamine molecule s were expressed. During marginal vitamin A deficiency, ciliary cells were specially labelled by GSA I-B. indicating presentation of termina l galactose molecules in alpha-position. Additionally, the cytoplasm o f epithelial cells demonstrated enhanced concentrations of polyantenna ry oligosaccharide core structures. Staining of epithelial cells by VV A was restricted to control specimens. Abundance of N-acetylglucosamin e residues on the non-reducing terminus of oligosaccharides was signif icantly enhanced in the connective tissue of depleted animals as demon strated by the binding patterns of GSA II. We suggest that altered oli gosaccharide patterns may contribute to enhanced predisposition to tra cheobronchial infection in marginal vitamin A deficiency.