S-IgA Associated with Streptococcus mutans and Caries in Children

Dental caries is an infectious disease, which has been associated with Streptococcus mutans in humans. The mucosal immune system produces salivary secretory immunoglobulin A (S-IgA) in response to this infection. Objectives: This study evaluates caries prevalence associated with S. mutans colonization and S-IgA activity in a high-caries-risk cohort. Methods: Decayed, missing, filled surfaces (dmfs) of primary teeth for 88 children (age 5-6 years) were recorded at baseline visits. Saliva samples were collected for analyses by ELISA of total and specific S-IgA activity against S. mutans. S. mutans was isolated from plaque samples from a group of 27 children (mean 13 isolates/child) for genotyping using repetitive extragenic palindromic-PCR. Results: Fifty-four children from this cohort (54/88=61%) were shown to have a history of dental caries (mean dmfs for caries positive group = 19). The caries positive group had a mean total S-IgA of 271μg/ml (median=183μg/ml), while the 34 caries-free-children had a mean of 191μg/ml (median=159μg/ml, difference was NS). Fourteen children were found to have only one S. mutans genotype (14/27=52%) a finding that was associated with lower dmfs (mean = 8.6) when compared to 13 children who had multiple genotypes (mean dmfs=19.2, p=0.030). Total S-IgA levels were significantly lower in the single genotype-group (mean=172μg/ml, median=160μg/ml) compared to the multiple S. mutans genotype-group (mean=323μg/ml, median=253μg/ml, p=0.048). However, specific S-IgA anti-S. mutans levels were higher in the single genotype group, but not significantly different from the multiple genotype group. Conclusion: Total S-IgA and number of S. mutans genotypes are positively correlated with the prevalence of dental caries in this cohort. A longitudinal assessment of S-IgA responses with dental caries and related specific S. mutans genotype may explain the association to dental caries in a high-risk population.

Supported by NIDCR research grant DE016684 & DART trainee grant DE017607