Salivary agglutinin and secretory IgA reactions with oral streptococci

S. mutans, S. salivarius, S. mitis and S. sanguis strains were isolated from three subjects of blood groups A, B and O. Parotid saliva samples obtained from the same subjects induced aggregation of some of the bacteria, the S. sanguis and the S. mutans strains in particular. While parotid saliva from the three subjects gave almost identical reactions, slight interindividual differences were observed for a few strains with the submandibular sublingual salivas. In parotid saliva, secretory antibodies reacting with all strains were present. The antibody levels differed between the three subjects but no specific pattern was observed when homologous strains were compared with heterologous strains.