Time-dependent alterations of 3-fucosyl-N-acetyl-lactosamine (CD15) expression in the endolymphatic sac of adult guinea pigs after glycerol administration.

The present study examined the effect of glycerol administration on 3-fucosyl-N-acetyl-lactosamine (CD15) epitope expression in the endolymphatic sac (ES) of the guinea pig's inner ear. Adult guinea pigs were injected intravenously with glycerol (2 g/kg body wt.). CD15 expression was studied at 80 min up to 5 h after treatment. In untreated animals single cells and cell groups in the ES expressing CD15 epitope intra- and intercellularly were identified by immunohistochemistry to be mainly in the epithelial layer of the rugosal and distal part of the sac. Glycerol administration modulated the expression of CD15 epitope. In the epithelial layer, expression decreased and was nearly depleted after 3 h. After 4 h of glycerol administration, CD15 expression reappeared and reached the comparable level of controls. The numbers of CD15-positive cells in the lumen of the ES increased steadily and arrived at their the highest levels in 2-h specimens. The localization of CD15-epitope expression and its modulation after glycerol administration within the ES implies that this molecule may play a role in re-establishing the sac's normal function. In addition, we speculate that CD15 may be associated with processes of an immune response in the inner ear.