Investigation of secretory immunoglobulins in saliva from germfree mice.

We investigated the effect of oral immunization on the serum and salivary immunoglobulin levels in axenic and conventional NIH mice. Specific antibacterial and antifungal antibodies were measured by passive hemagglutination, and differences in the immunoglobulin classes were measured by radial immunodiffusion. After an oral immunization regimen with either intact Escherichia coli or Candida albicans, a significant increase in specific antibody above the base-line reciprocal titer of 32 was observed in conventional mouse saliva. Saliva from axenic mice immunized with the formalized microorganisms yielded reciprocal antibody titers of 256, as compared with an absence of specific antibodies in control animals. Assay of the sera of both groups of immunized mice revealed no increase in antibody levels specific for E. coli lipopolysaccharide or Candidin.