Immunological relationship between anionic antimicrobial proteins from caries-free individuals and known salivary antimicrobial factors.

We examined whether the anionic inhibitory proteins identified in mixed saliva from certain caries-free individuals are fragments or degradation products of recognized salivary antimicrobial factors. In the experiments reported here, the anionic inhibitory proteins did not produce precipitin reactions with antisera to any of the established salivary antimicrobial factors examined. Additionally, native, heat-treated, or urea-denatured known salivary antimicrobial factors did not react with the antiserum to the anionic inhibitory proteins. However, the antiserum to the anionic inhibitory proteins was found to be reactive with a protein concentrate from mixed saliva or from separate submandibular and parotid secretions from a number of different donors, as well as with a purified protein fraction containing the homologous anionic inhibitory proteins. These findings suggest that the anionic inhibitory proteins represent intact and unique salivary proteins and not the degradation fragments of salivary antimicrobial protein factors within the oral environment.