Inhibition of lectin-binding to saliva-treated hydroxyapatite, to buccal epithelial cells, and to erythrocytes by salivary components.

The influence of human saliva on the binding of several lectins to saliva-treated hydroxyapatite surfaces which mimic the teeth, to buccal epithelial cells, and to erythrocytes was determined. Clarified whole saliva inhibited binding of 3H-labeled concanavalin A, wheat germ, soy bean, Ulex europaeus, and peanut agglutinins to saliva-treated hydroxyapatite by 75 to 95%, depending on lectin concentration used. Different fractions of saliva-inhibited binding of different lectins. For example, salivary mucins reduced the binding of wheat germ agglutinin to saliva-treated hydroxyapatite, but they did not significantly affect binding of other lectins studied. Components of saliva also inhibited lectin-mediated hemagglutination. Using an indirect enzyme-linked immunoassay, wheat germ and peanut agglutinins were found to bind in a specific manner to human buccal epithelial cells, and this was also greatly reduced by saliva. The data suggest that one of the major functions of salivary and other alimentary secretions may be to reduce the extent of interaction of dietary lectins with mucosal surfaces.