Priming Effect of Porphyromonas gingivalis Lipopolysaccharide on Superoxide Production by Neutrophils From Healthy and Rapidly Progressive Periodontitis Subjects

P re‐incubation of neutrophils from rapidly progressive periodontitis (RPP) patients with lipopolysaccharide (LPS) extracted from Porphyromonas gingivalis was found to prime the neutrophils for enhanced FMLP‐stimulated superoxide production in a dosedependent manner. The priming effect of P. gingivalis LPS on neutrophils from control subjects was scanty or without effect at all. Inclusion of human serum in the experimental priming conditions increased the control and RPP neutrophil response by 2 to 3 fold. Blocking of the CD14 receptor on the neutrophil surface with monoclonal antibody eliminated the priming effect. Furthermore, incubation of control neutrophils with P. gingivalis LPS in the presence of serum from RPP patients generated a higher response as compared to incubation with control serum. The data suggest that neutrophil priming described in RPP patients is dependent on a serum factor which alters the neutrophil response to priming agents such as LPS. J Periodontol 1994;65:129–133 .