Effect of amine and stannous fluoride on human neutrophil functions in vitro

Amine fluoride (AmF)- and stannous fluoride (SnF2)-containing products were found to have a therapeutic effect on gingivitis and periodontitis. This effect was suggested to correlate with the antibacterial activity of the fluoride compounds. However, their effect on inflammatory cell function can also play a role in the therapeutic effect on gingival inflammation. The present study was designed to test the effects of AmF, SnF2, and an AmF/SnF2 combination on the function of human peripheral blood neutrophils, as compared with effects of chlorhexidine and salicylic acid. Neutrophils were isolated from human blood by ficoll centrifugation followed by dextran sedimentation. The neutrophils were pre-incubated with AmF, SnF2, or AmF/SnF2, followed by stimulation with fMLP. Cell vitality was verified by trypan-blue exclusion (> 95% vitality at all tested concentrations). Superoxide production was measured by cytochrome C reduction and the enzymatic activity of lysozyme and beta-glucoronidase by optical density measurement of substrate conversion. The results showed that AmF, SnF2, or AmF/SnF2 enhanced by two- to three-fold the superoxide release from fMLP-stimulated human neutrophils. Furthermore, the effective concentration of the AmF/SnF2 combination was several-fold lower than that of AmF or SnF2 alone (10 nM for AmF, 0.5 microM for SnF2, and 3 pM for SnF2/AmF). On the other hand, chlorhexidine and salicylic acid were found to reduce superoxide production by the cells. All the tested compounds had no effect on granular enzyme release by the stimulated neutrophils. The results suggest that AmF and SnF2 enhance the oxygen-dependent antibacterial activity of neutrophils. This effect may contribute to a more efficient elimination of bacteria from the periodontal environment, resulting in improvement in gingival health.