Human serum antibody response against Streptococcus mutans antigens.

Antigens from Streptococcus mutans were examined to identify specific polypeptides that may have stimulated antibody responses and possibly play some role in caries immunity. A group of 10 adult human subjects was screened for serum antibodies reactive with antigens from S. mutans. Extracellular and cellular protein preparations from S. mutans LM7 (Bratthall serotype e) and V403 (biotype c) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western electrophoretic transfer and immunoblotting analysis. Antibodies reactive with polypeptides ranging from 34 to 400 kilodaltons in apparent molecular mass were detected by these means. Radioimmunoassay competition experiments revealed that the cellular and extracellular antigens did not compete with each other for serum antibodies. Preabsorption of sera with extracellular proteins from other oral streptococcal species prior to immunoblotting indicated that the antigens unique to S. mutans have molecular masses greater than 100 kilodaltons, and each individual produced antibodies against different antigens of high molecular mass. Examination of sera from young children also indicated heterogeneous responses against S. mutans LM7 antigens.