Immunoglobulin A antibodies to mutans streptococci in human saliva and serum comparing fresh and subcultivated strains and activity in repeated saliva samples.

The aims of this study were i) to characterize and compare the sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein patterns of reference Streptococcus mutans and Streptococcus sobrinus strains, subcultivated for years, with fresh isolates of the same serotype; ii) to study possible differences between the human salivary immunoglobulin A (IgA) activity to reference strains and to fresh bacterial isolates of the saliva donors; iii) to examine for potential differences in the salivary IgA activity to the streptococcal antigens during 1 week; and iv) to map, in the same individuals, the serum IgA activity against the selected bacteria. S. mutans reference and fresh isolated strains showed a similar protein pattern with few exceptions. The immunoblot also revealed similarity in saliva IgA response, with only one subject's saliva displaying clearly one band's difference. For S. sobrinus a larger discrepancy was seen. The antibody activity during the one week interval was essentially unchanged. When incubated with serum, a different immunoblot profile was seen compared with saliva, although most bands revealed by saliva were also displayed by serum.