The induction of salivary antibodies by topical sensitization with particulate and soluble bacterial immunogens

This investigation attempted to characterize systematically the secretory and serum immune responses following oral administration of soluble and particulate bacterial immunogens. Following oral sensitization of axenic mice with Escherichia coli lipopolysaccharide, Candidin, or streptococcal group H antigen, a substantially longer latent period was observed before all salivary samples exhibited specific agglutinins when compared to a similar immunization regimen with intact nonviable micro-organisms. Also, the peak titres of salivary agglutinins were significantly lower when the soluble antigenic counterparts of particulate E. coli or Candida albicans were utilized as immunogens. Examination of serum antibodies showed that following administration of E. coli LPS, similar titres of exocrine and serum agglutinins were noted. The serum titres were significantly greater (P less than 0.01) than those elicited by oral immunization with particulate E. coli. After termination of the topical immunization regimen, salivary agglutinins were found to decline rapidly whether immunization was via soluble or particulate antigens; however, immunization with particulate bacterial antigens appeared capable of stimulating and maintaining a higher rate of local antibody secretion than similar sensitization with soluble immunogen preparations.