Inhibitory effect of lactoferrin on the adhesion of Prevotella nigrescens ATCC 25261 to hydroxyapatite.

Prevotella nigrescens ATCC 25261 (P. nigrescens) cells adhere well to hydroxyapatite treated with citrate (CHA), but the attachment is drastically inhibited by lactoferrin (LF). To determine the nature of the iron-free LF responsible for inhibiting P. nigrescens cell attachment, this study tested the duration and frequency of LF treatment of CHA and the effects of divalent and trivalent ferric ions. The inhibitory effect on the attachment of P. nigrescens was somewhat higher with bovine LF than human LF. Apo LF effectively inhibited P. nigrescens cell attachment to CHA, and almost abolished attachment at a concentration of 0.4 mg/ml. Fe3+ saturated LF was unable to inhibit attachment, whereas Fe2+ showed a slight effect under the same conditions. The LF absorbed rapidly to CHA in less than 10 min. With a lower concentration (0.1 mg/ml) of LF, only three treatments of CHA were required for the maximum inhibition of P. nigrescens cell attachment. The quantity of LF adsorbed to the hydroxyapatite (HA) and to P. nigrescens cells was determined by use of [3H]-LF. Approximately 25 micrograms of LF protein adsorbed to 5 mg of HA at saturation, and approximately 0.25 microgram of LF did so to the 6 x 10(8) cells.