Immunoglobulin A reaction to oral streptococci in saliva of subjects with different combinations of caries and levels of mutans streptococci.

The aim of this study, performed in Bangkok, was to study whether a particular salivary immunoglobulin A (IgA) antibody profile against mutans streptococci could be related to the absence or presence of caries. A group of 12-year-old individuals representing various combinations of mutans streptococci levels and caries experience was selected. Whole saliva stimulated by paraffin-chewing was collected, and the children were investigated for decayed, missing and filled surfaces (DMFS) and teeth (DMFT), following WHO criteria and methods, at baseline and after 2 years. The total amount of salivary IgA was determined by an immunobead enzyme-linked immunosorbent assay, and SDS-PAGE and Western blot analysis was performed using sonicated antigens of Streptococcus mutans and Streptococcus sobrinus strains and, as a control, a Streptococcus parasanguis strain. The results showed that Thai children with low caries prevalence had more distinct immunoblot bands to antigens from mutans streptococci than did the high-caries children. A similar picture was not seen for S. parasanguis. On the whole, the Thai children also showed fewer bands than usual Swedish saliva samples from comparable age groups. The complexity of the relationship between dental caries and IgA in saliva is highlighted.