DIFFERENCES IN TERMINAL CARBOHYDRATE STRUCTURES OF SIALOMUCIN IN THE MURINE NASAL CAVITY

Terminal carbohydrate structures of sialomucin in the murine nasal cav ity were characterized by means of lectin histochemistry. Two kinds of biotinylated lectins (Maackia amurensis agglutinin and Sambucus nigra agglutinin), which recognize sialic acid residues, showed marked diff erences in their respective labeling patterns when used as epithelial probes. Maackia amurensis agglutinin labeled the epithelial goblet cel ls, Bowman's glands, and all cell surfaces of both olfactory and respi ratory epithelium. In contrast, Sambucus nigra agglutinin labeled cell surfaces and Bowman's glands in the murine olfactory epithelium, but did not label the murine respiratory epithelium. These results indicat e that sialomucin in the murine nasal cavity has two different termina l carbohydrate structures. Our data show that sialomucin in the murine respiratory epithelium has a Neu5Ac(alpha2-3)Gal sequence, while sial omucin in the murine olfactory epithelium has both alpha2-3 and alpha2 -6 binding sequences. These results suggest that different carbohydrat e structures of sialomucin in the nasal cavity may reflect differences in susceptibility to bacterial colonization and viral infection betwe en respiratory and olfactory epithelium, and influence rheological pro perties of nasal secretion.