Immunological cross-reactivity of anionic proteins from caries-free and caries-active salivas which differ in biological properties toward oral streptococci.

We examined whether the anionic antimicrobial proteins in the saliva of certain caries-free (CF) individuals are immunologically cross-reactive with proteins in caries-active (CA) saliva which display identical isoelectric points but which exhibit growth-supportive properties for the oral streptococci. In the immunoblotting experiments reported here, the proteins present in CF and CA whole salivas reacted similarly with an antiserum prepared against the anionic inhibitory proteins. This antiserum also showed identical reactivity with the purified protein fraction containing the anionic proteins of interest from whole saliva of either CF or CA subjects. Additionally, an antiserum to CA saliva was found to react with the CF anionic inhibitory proteins. The fact that the inhibitory and noninhibitory proteins react similarly with the antisera used provides further evidence for similarity between both classes of proteins.