Expression of salivary mucin bacterial aggregating activity: difference with caries.

The low and high molecular weight mucin forms were isolated from saliva of individuals with different caries status and assessed for their bacterial aggregating potential towards S. mutans and S. sanguis. The high molecular weight mucin from both groups exhibited similar protein and carbohydrate content, but the level of covalently bound fatty acids was lower in the caries-resistant group. The mucin from caries-resistant group showed only a weak inhibitory potential, while no inhibitory activity was observed with the mucin of caries-susceptible group. The low molecular weight mucins from both groups, while displaying compositional similarities, showed a marked variation in the bacterial aggregating activity, and the titer of the mucin from caries-resistant group was at least 128-fold greater than that of caries-susceptible group. The results demonstrate that the bacterial aggregating epitope of salivary mucins is expressed to a greater extent in caries-resistant individuals, and that this epitope is apparently more accessible to bacteria in the low molecular weight mucin form.