Sequential appearance of salivary antibodies after oral immunization of axenic mice.

The purpose of the present investigation was to examine the production of specific salivary antibodies after oral immunization of axenic mice (ICR/CD-1) with formalinized Escherichia coli (ATCC 11775). Three aspects of the humoral response were studied: (i) the sequential appearance of anti-E. coli antibodies; (ii) classes of antibodies produced in response to the antigen; and (iii) antibody specificity. Antibody levels were determined by passive hemagglutination with soluble lipoplysaccharide and bacterial agglutination, using preparations of somatic O and flagellar H antigens. A short latent period of 1 to 3 days was observed when saliva samples were assayed for anti-lipopolysaccharide and anti-O antibodies. The salivary antibody titers peaked at 11 days after initiation of the immunization regimen. Only two of six mice exhibited a change in serum antibody levels against these antigens. The predominant class of early antibody in saliva was immunoglobulin (Ig)G; however by 7 days IgA WAS found to comprise the major portion of specific immunoglobulins. Serum antibodies directed against falgellar antigenic determinants were primarily of the IgM class, whereas the salivary antibodies were IgG in nature.