Differential recognition of oral indigenous bacteria by salivary immunoglobulins A and G.
Assuming that salivary immunity to indigenous microorganisms could develop, we assessed antibacterial reactivities of natural salivary antibodies in specific pathogen-free inbred mice. An ELISA was set up, using whole bacterial cells, to map reactivities of salivary IgA and IgG which accounted respectively for 91% and 8.7% of salivary Ig's in the BALB/c mouse. Representative strains of seven species from three genera (Lactobacilli, Staphylococci, and Streptococci), including major and minor components of the murine oral flora (38, 43, and 8%, respectively), were used to determine the presence and level of specific antibodies in individual saliva. It was verified that naturally occurring IgA antibodies can display diverse antibacterial reactivities. A characteristic profile emerged for salivary IgA where antibodies to Streptococcus faecalis predominate. Natural salivary IgG antibodies did not show the same reactivity pattern as IgA, anti-Lactobacilli and anti-Staphylococci reactivities being much less frequent in the salivary IgG repertoire. However, antibodies to S. faecalis occurred at the same high frequency for both isotypes (62-70% of the samples). Besides being species-specific, antibacterial reactivities were also found to be strain-specific. Broad variations in antibacterial titers were detected among individual mice under standardized experimental conditions. Present data thus suggest that the dynamics of salivary antibody production in the mouse reflect a differential natural sensitization of the secretory (IgA) versus the systemic (IgG) immune systems by distinct populations of indigenous bacteria.
D000818:Animals; D001419:Bacteria / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D007071:Immunoglobulin A, Secretory / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D007778:Lactobacillus / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009055:Mouth / Q000382:microbiology*; D012463:Saliva / Q000276:immunology*; D013047:Specific Pathogen-Free Organisms; D013210:Staphylococcus / Q000276:immunology; D013291:Streptococcus / Q000276:immunology
D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G