The oral immune system: dynamics of salivary immunoglobulin production in the inbred mouse.

In the oral cavity, salivary immunoglobulins (Igs) are the principal mediators of specific immunity. Using carbachol to stimulate saliva flow, we investigated, in a kinetic study, individual variations in salivary Ig concentrations in 23 adult BALB/c mice using an enzyme-linked immunosorbant assay (ELISA). It appeared that salivary Ig concentrations are highly variable in individual mice (IgA: 3-81 micrograms/mL; IgG: 0-2.9 micrograms/mL; IgM: 0.002-0.14 microgram/mL). In individual mice stimulated at different times over a 3 week period there are considerable variations both in salivary Ig concentrations and in their respective ratio. Broad variations were also found in the levels of specific IgA and IgG antibodies to three indigenous oral murine bacteria. Present data thus indicate that among genetically identical mice of the same age and sex, sharing identical diet, there is considerable heterogeneity in salivary Igs. As this heterogeneity was mimicked at the cellular level in major and minor salivary gland-associated B-cells, it appears that antibody dynamics in the oral cavity could reflect the adaptive capacity of the oral immune system to local antigenic challenge.