Effect of priming in subpopulations of peripheral neutrophils from patients with chronic periodontitis

Patients with periodontal disease are reported to generate more reactive oxygen species (ROS) than matched controls, suggesting increased inflammatory defense activity. The purpose of this study is to determine whether there are subpopulations of peripheral neutrophils in patients with chronic periodontitis (CP) that generate different levels of intracellular ROS when primed with tumor necrosis factor-α (TNF-α) or the chemokine interleukin-8 (IL-8, CXCL8) compared to controls.

Venous blood was collected from 13 patients with CP despite careful maintenance over 2 to 8 years and from 13 healthy age- and sex-matched controls. Neutrophils were separated from whole blood over a Percoll gradient and then activated via the Fcγ receptor with opsonized Staphylococcus aureus after priming with TNF-α or IL-8. The samples were analyzed by flow cytometry using the fluorescent probe dihydrorhodamine 123. Generation of ROS was measured as the intensity of fluorescence (IFL).

Two subpopulations were found in both patients and controls: one with low and one with high generation of IFL. The subpopulation with high generation of IFL in patients with CP was more responsive to IL-8 (P <0.05) than the same subpopulation in healthy controls. No other differences in generation of ROS or priming effects were found between patients with CP and controls. Generation of ROS was dependent on nicotinamide adenine dinucleotide phosphate oxidase, and the intracellular ROS was primarily the oxygen anion.

Patients with CP had a subpopulation of peripheral neutrophils that were more responsive to IL-8 priming than controls.