Effect of local deposition of antigen on salivary immune responses and reaccumulation of mutans streptococci

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Abstract
In this study glucosyltransferase (GTF) fromStreptococcus sobrinus was topically administered onto the lower lips of young adults. The effect of this route of antigenic exposure on labial and parotid gland and serum antibody levels to GTF and on the reaccumulation of indigenous mutans streptococci after a dental prophylaxis was then measured. Young adults between 18 and 42 years of age were screened for levels of antibody activity to GTF in parotid and labial gland salivas and levels of mutans streptococci in their whole saliva. Prior to antigen administration, two groups were formed which had similar distributions of mutans streptococci in their whole saliva. Antigen (GTF) or placebo, each combined with aluminum phosphate (AP), was then administered to the lower lip daily for 5 days. Immediately prior to topical application of GTF or placebo to the labial salivary glands, all subjects were given a dental prophylaxis. Statistically significant differences in anti-GTF IgA antibody activity in parotid or labial salivas were not observed between the GTF-administered and the placebo groups during the 6 weeks following topical application. However, the proportions of indigenous mutans streptococci/total streptococcal flora, or total cultivable flora, were always lower in the whole salivas of the GTF, compared with the placebo group. These differences were statistically significant on days 13, 20, 34, and 41 after initial topical application. Delays in reaccumulation were significantly associated (P<0.025) with elevations in parotid saliva IgA antibody levels of all subjects. Seven of 10 of the subjects demonstrating this association were in the group to which GTF was topically administered. These results suggest that labial application of GTF in aluminum phosphate can modify the salivary immune environment to retard the reaccumulation of indigenous mutans streptococci after a dental prophylaxis.