Abstract: Objective: To investigate the production of reactive oxygen species (ROS) from polymorphonuclear cells (PMNs) stimulated by porphyromonas gingivalis (P. gingivalis, Pg) or aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans, Aa) when co-infected with fusobacterium nucleatum (F. nucleatum, Fn) . Methods: Venous blood of healthy volunteers was obtained with heparin anticoagulation, the PMNs isolated with Percoll was mixed separated with 2’,7’-Dichlorodihydrofluorescindiacetate (DCFH-DA) and then incubated for 15 min in water bath at 37℃. Bacteria of group A and B (groups: A1, Pg; A2, Aa; A3, Fn;B1, Pg + Fn; B2, Aa + Fn; B3, Pg + Aa; B4, Pg + Aa + Fn; B5, Aa + Pg + Fn)were added into the tube for sufficient mixing, and then was incubated (37℃) for 1h and 4h. The amount of ROS produced by PMNs was measured by flow cytometry. Results: After the reaction of periodontopathic bacteria and isolated PMNs at 37℃ for 1h and 4h, the ROS production amounts were respectively A1-16.52; A2-18.74; A3-19.59; B1-17.60; B2-20.09. Among them, B1>A1, and B2>A2 (P<0.05). At the time of 4h, the amounts of ROS production were respectively A1-176.05; A2-203.19; A3-230.36; B1-259.08; B2-274.89. Among them, B1>A1 and B2>A2 (P<0.05). Conclusion: These results suggested that the production of ROS from PMNs by Pg and Aa can be enhanced when co-infected with Fn.

Key words: Polymorphonuclear cells , Reactive oxygen species, Fusobacteriumnucleatum, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans