Detachment of oral bacteria from saliva-coated hydroxyapatite by human polymorphonuclear leukocytes

Human polymorphonuclear leukocytes (PMN) demonstrated the ability to detach Actinomyces viscosus, A. naeslundii and Streptococcus sanguis from saliva-coated hydroxyapatite beads (SHA). Between 60 to 80% of bacteria were detached within 1 hour at PMN-to-bacteria ratios between 1:10 to 1:22. Detachment was enhanced by treating bacteria with fresh but not heat-inactivated normal human serum. Detachment of serum-treated A. viscosus was inhibited by cytochalasin B, L-1-tosylamide-2-phenylethylchloromethyl ketone (TPCK), and deoxyglucose but not colchicine, phenylmethylsulfonyl fluoride (PMSF), N-carbobenzoxy-L-phenylalanine chloromethyl ketone (ZPCK), and sodium azide. In the absence of serum treatment, the detachment of A. viscosus was insensitive to lactose, galactose, and mannose. We conclude that PMN can efficiently detach bacteria from SHA, this detachment is enhanced by serum, and this enhancement is probably dependent upon complement. Additionally, detachment of A. viscosus bound to SHA by PMN (1) does not appear to involve bacterial lectin activity, (2) seems to be dependent upon glycolytic metabolism, microfilament formation, and the activity of a TPCK-sensitive serine protease, and (3) is not sensitive to inhibitors of tubulin polymerization or heme-protein activity.