Phagocytosis of periodontopathogenic bacteria by crevicular granulocytes is depressed in progressive periodontitis

Background: The aim of this study was to examine crevicular polymorphonuclear neutrophils (PMN) of patients with rapidly progressive periodontitis (RPP) for their in vitro phagocytic activity and intracellular killing of Porphyromonas gingivalis ATCC 33277 and two strains of Actinobacillus actinomycetemcomitans (NCTC 9710 - type strain and Tanner FDC 44 - leukotoxin producing strain). Patients and Methods: 18 patients with RPP and nine healthy controls were included in the study. Phagocytosis and intracellular killing were assessed by fluorescence microscopy after staining with acridine orange. The percentage of phagocytosing PMN was determined. The phagocytic cells were then separated into two groups; those containing < 10 phagocytosed bacteria and those containing > 10 bacteria. The percentage of PMN containing viable bacteria was also determined. Results: The leukotoxic A. actinomycetemcomitans strain was phagocytosed to a lesser degree than the corresponding type strain. The number of phagocytosing cells obtained from the RPP patients did not differ from the controls. However, in healthy subjects there were more phagocytes with more than ten ingested P. gingivalis than in RPP patients. The intracellular killing was diminished in the periodontitis group for P. gingivalis and for both A. actinomycetemcomitans strains. Conclusion: The PMN of patients with RPP show deficiencies in phagotcytic activity and in the intracellular killing or peridontopathogenic bacteria.