EXPRESSION OF GLYCOCONJUGATES IN HUMAN EUSTACHIAN TUBES WITH OTITIS-MEDIA

Objectives: To characterize glycoconjugate expression in normal human eustachian tubes and study the alterations in glycoconjugate expressio n found in eustachian tubes with otitis media. Study Design: Using lec tin histochemistry, alterations in glycoconjugates were studied in thr ee normal temporal bones, in four temporal bones with mucoid otitis me dia (MOM), and in five with serous otitis media (SOM). Methods: Sectio ns of previously processed temporal bones were decelloidinized, and th en incubated with seven biotinylated lectins-WGA, SNA, MAA, BPA, PNA, UEA-1, and LcH-that reflect seven carbohydrate residues of glycoconjug ates, respectively: GlcNAc/NeuNAc, NeuNAc alpha(2-6)GalNAc, NeuNAc alp ha(2-3)GalNAc, Gal beta(1-3) GlcNAc, L-fucose, and alpha-mannose resid ues. Control sections were incubated with inhibitory carbohydrates or without biotinylated lectins. Results: In the normal temporal bones, f ive carbohydrate residues in goblet cells and cilia of the eustachian tube demonstrated moderate to strong activity-NeuNAc alpha(2-6)GalNAc, NeuNAc alpha(2-3)GalNAc, GalNAc, Gal beta(1-3)GalNAc, and L-fucose. T wo residues demonstrated weak activity-GlcNAc/NeuNAc and alpha-mannose . Temporal bones with MOM revealed increases in sialic acid and alpha- mannose, and a decrease in L-fucose. Residues of carbohydrates in the cilia of bones with SOM were notably decreased, especially for GalNAc, Gal beta(1-3)GalNAc, and NeuNAc alpha(2-6)GalNAc. Conclusions: Glycoc onjugates in the normal human eustachian tube are rich in GalNAc, Gal beta(1-3)GalNAc, L-fucose, and NeuNAc alpha(2-3/2-6) GalNAc, but low i n alpha-mannose and sialic acid. Eustachian tubes from cases with SOM or MOM demonstrated alterations in glycoconjugate expression in cilia and goblet cells, which may reflect disorder of the carbohydrate metab olism during otitis media, especially in SOM.