Inhibition of streptococcal attachment to receptors on human buccal epithelial cells by antigenically similar salivary glycoproteins.

Preparations of salivary glycoproteins inhibited the attachment of certain indigenous oral streptococci to human buccal epithelial cells and fostered the desorption of previously attached bacteria. The adherence-inhibiting and desorptive activities of the glycoproteins correlated with their ability to aggregate these organisms. Pretreatment of glycoprotein preparations with certain blood group antisera impaired their adherence-inhibiting effect, suggesting that components with blood group substance reactivity were involved. Pretreatment of buccal epithelial cells with certain blood group antisera or concanavalin A masked the receptors associated with the attachment of Streptococcus sanguis SG1. The association of blood-group-reactive substances with the receptors involved in bacterial attachment may provide a basis for understanding the distinct specificities that bacteria exhibit for attaching to different tissues, organs, and hosts. Antiserum raised in rabbits to human epithelial cells also exhibited receptor-masking activity, and absorption of this serum with homologous salivary glycoproteins removed the antibodies responsible. These observations indicate that some salivary glycoproteins are antigenically similar to components on the epithelial cell surfaces they bathe. It is suggested that by mimicking the receptors present on epithelial cells, the mucinous glycoproteins of secretions may competitively inhibit the sorption of infectious agents and facilitate their removal after they are attached. These activities help to explain how mucinous glycoproteins augment the cleansing action of secretions.