DIFFERENTIAL EXPRESSION OF SALIVARY MUCIN BACTERIAL AGGREGATING ACTIVITY WITH CARIES STATUS

1. The low and high mol. wt mucin forms were isolated from saliva of c aries-resistant (CR) and caries-susceptible (CS) individuals, and asse ssed for their bacterial aggregating potential towards S. mutans and S . sanguis, the common cariogenic microorganisms encountered in the ora l cavity. 2. The high mol. wt mucin from both groups of subjects exhib ited similar protein and carbohydrate content, but the level of covale ntly bound fatty acids was significantly lower in the CR group. The mu cin from CR group showed only a weak inhibitory potential, and no inhi bitory activity was observed with the mucin of CS group. 3. The low mo l. wt mucins from both groups, while displaying compositional similari ties, showed a marked variation in the bacterial aggregating activity. With both bacteria, the activity of the mucin from CR group was at le ast 128-fold greater than that of CS group. 4. The conversion of the h igh mol. wt mucin to a low mol. wt form through the action of salivary protease produced in both groups enhancement in mucin's bacterial agg regating capacity. This enhancement was, however, considerably less pr onounced in the case of mucin from CS group. 5. The results for the fi rst time demonstrate that the bacterial aggregating epitope of salivar y mucins is expressed to a greater extent in CR individuals, and that this epitope is apparently more accessible to bacteria in the low mol. wt mucin form.