The interactions of human neutrophils with the constituents of an experimental dental biofilm

Despite the antibacterial properties of neutrophils, their ability to prevent colonization of the dental biofilm by pathogenic bacteria is limited. The present study examined the ability of human neutrophils to attach to an experimental dental biofilm and tested their antibacterial functions following adhesion. Neutrophil adhesion was greatest to hydroxyapatite (HA) in the absence of biofilm. Among the biofilms, glucosyltransferase or fructosyltransferase adsorbed onto saliva-coated HA showed the highest adhesion of cells. The adhesion of neutrophils was directly related to their initial concentration in the solution and to the duration of incubation. Plasma was found to reduce neutrophil attachment significantly, while stimulation of the cells had no effect. Stimulation of attached neutrophils induced superoxide secretion with levels significantly lower than that secreted by suspended cells. The presence of neutrophils on the biofilm reduced the number and the viability of Streptococcus mutans attached to the beads. The present findings suggest that neutrophils are able to attach to dental biofilms and that the attached neutrophils retained their antibacterial activity.