Binding of Streptococcus mutans, Serotype c, to Saliva-coated Hydroxyapatite in the Presence and Absence of Human Lactoferrin

Abstract

The adhesion of ³H-labelled Streptococcus mutans (serotype c) cells to spheroidal hydroxyapatite (HA) beads was studied by precoating HA with whole saliva with or without the presence of human lactoferrin (LF). Treatment of HA with LF-free saliva prevented the streptococcal adhesion more strongly than treatment with buffer alone. However, supplementation of LF-free saliva by iron-free LF (apo LF), or partly or totally Fe³⁺-saturated LF (200 mg/1), significantly enhanced (P<0001) the inhibition. No notable differences existed between the various forms of LF. The inhibition of bacterial adherence was dose dependent with respect to the amount of LF bound to saliva-coated HA (SHA), suggesting a non-specific protein blockage. Significant (P<0001) inhibition was observed with apo LF concentration as low as 10 mg/1. LF-mediated inhibition of the adherence of S. mutans, serotype c, to SHA is obviously non-specific, antibacterial function for this innate defence protein which is present in human saliva, gingival crevicular fluid and also as an integral part of the acquired salivary pellicle in vivo.

Key Words:

• Streptococcus mutans
• Lactoferrin
• Bacterial adhesion
• Saliva
• Antimicrobial agents