Histochemical study of the epithelia of nasal polyps by biotinylated lectins and neoglycoprotein. A comparison with the normal human respiratory epithelium.

Formalin-fixed, paraffin-embedded sections from human nasal polyps and the normal respiratory epithelium were glycohistochemically investigated. Three biotinylated lectins were used: peanut (Arachis hypogaea) agglutinin (PNA) which, binds to terminal galactose (beta 1-3) N-acetylgalactosamine residues that can be unmasked by a neuraminidase digestion; wheat germ (Triticum vulgare) agglutinin (WGA), which binds to N-acetylglucosamine and N-acetylneuraminic acids; and gorse seed (Ulex europaeus) agglutinin (UEA-1), which binds to L-fucose. In addition, the presence of accessible galactose (beta 1-3) N-acetylgalactosamine (T-antigen) glycan receptors (endolectins) was also assessed. The avidin-biotin-peroxidase complex (ABC) and diaminobenzidine (DAB) were used as chromogen. The ciliated cells of the normal respiratory epithelium and those of the pseudostratified epithelium of nasal polyps possess similar glycohistochemical characteristics suggesting no major alterations on the level of lectin-reactive carbohydrate epitopes as indicators of cellular glycosylations. Notably, this parameter can respond sensitively to changes in cell differentiation or activation. The basal and mucus-secreting cells in the two epithelia display different reactivity patterns emphasizing the presence of dissimilar sugar residues. Similarly, the dysplasia reflecting squamous epithelium of nasal polyps shows a distinct staining behaviour, indicative for disparate glycoconjugate display. Thus, quantitative differences in the lectin-selective staining of various cell types are detectable. The expression of T-antigen-bearing neoglycoprotein binding is weak and similar in both the normal epithelium and the pseudostratified epithelium lining nasal polyps. Only the most superficial cells of the squamous epithelium disclose a moderate labelling with this probe. These results indicate that further studies in this field are warranted, employing neoglycoproteins and also endolectins from human tissues to correlate glycobiological properties of the epithelium of the conducting airways and its diseased forms with functional features.