title: Mast cells act as phagocytes against the periodontopathogen Aggregatibacter actinomycetemcomitans.
abstract: BACKGROUND
  Evidence to date shows that mast cells play a critical role in immune defenses against infectious agents, but there have been no reports about involvement of these cells in eliminating periodontopathogens. In this study, the phagocytic ability of mast cells against Aggregatibacter actinomycetemcomitans compared with macrophages is evaluated.
  
  
  METHODS
  In vitro phagocytic assays were conducted using murine mast cells and macrophages, incubated with A. actinomycetemcomitans, either opsonized or not, with different bacterial load ratios. After 1 hour, cells were stained with acridine orange and assessed by confocal laser-scanning electron microscopy.
  
  
  RESULTS
  Phagocytic ability of murine mast cells against A. actinomycetemcomitans was confirmed. In addition, the percentage of mast cells with internalized bacteria was higher in the absence of opsonization than in the presence of opsonization. Both cell types showed significant phagocytic activity against A. actinomycetemcomitans. However, the percentage of mast cells with non-opsonized bacteria was higher than that of macrophages with opsonized bacteria in one of the ratios (1:10).
  
  
  CONCLUSIONS
  This is the first report about the participation of murine mast cells as phagocytes against A. actinomycetemcomitans, mainly in the absence of opsonization with human serum. Our results may indicate that mast cells act as professional phagocytes in the pathogenesis of biofilm-associated periodontal disease.
authors.affiliation: Department of Stomatology, Bauru School of Dentistry, São Paulo University, Bauru, SP, Brazil.
authors.forename: Heliton G
authors.initials: HG
authors.lastname: Lima
authors.forename: Karen H
authors.initials: KH
authors.lastname: Pinke
authors.forename: Taiane P
authors.initials: TP
authors.lastname: Gardizani
authors.forename: Devandir A
authors.initials: DA
authors.lastname: Souza-Júnior
authors.forename: Daniela
authors.initials: D
authors.lastname: Carlos
authors.forename: Mario J
authors.initials: MJ
authors.lastname: Avila-Campos
authors.forename: Vanessa S
authors.initials: VS
authors.lastname: Lara
mesh_terms: D000165:Acridine Orange; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology*; D000818:Animals; D058491:Bacterial Load / Q000276:immunology; D018441:Biofilms; D001854:Bone Marrow Cells / Q000276:immunology; D018929:Cell Culture Techniques; D004926:Escherichia coli / Q000276:immunology; D005456:Fluorescent Dyes; D006801:Humans; D008264:Macrophages / Q000276:immunology; D008297:Male; D008407:Mast Cells / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D010510:Periodontal Diseases / Q000276:immunology / Q000382:microbiology*; D010586:Phagocytes / Q000276:immunology* / Q000382:microbiology; D010587:Phagocytosis / Q000276:immunology; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D000165:Acridine Orange