title: Toll-like receptor 2 expression in refractory periapical lesions.
abstract: OBJECTIVE
  To investigate the expression of TLR2 in refractory periapical lesions.
  
  
  METHODS
  Refractory periapical lesion biopsies were histopathologically and clinically categorized into asymptomatic periapical granuloma (n=10), symptomatic periapical granuloma (n=10) or periapical cyst (n=10) and prepared for immunohistochemical staining using antibodies to TLR2, CD3 and CD19 or staining with methyl green pyronin. Sections were viewed under light microscopy and the presence or absence of the target cells was correlated with the histopathological and clinical data. Additionally, TLR2 expression was quantified by counting TLR(+) cells.
  
  
  RESULTS
  Various mononuclear inflammatory cells in the bacteria-induced periapical lesions were reactive to TLR2 antibody, with many showing morphological similarities to lymphocytes and plasma cells. Lymphocytes were the most numerous cells in the inflammatory infiltrate. In refractory periapical granuloma, CD3(+) T cells were more numerous, whereas in periapical cysts, CD19(+) B cells were more numerous. There was a statistically significant (P<0.05) higher expression of TLR2 in symptomatic periapical granuloma than asymptomatic periapical granuloma or periapical cyst.
  
  
  CONCLUSIONS
  The presence of TLR-expressing cells in periapical granulomas and cysts provides further evidence that periapical cysts are likely to be sustained by the immune system via reaction to bacterial antigens.
authors.affiliation: Department of Oral Rehabilitation, Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand.
authors.forename: S V
authors.initials: SV
authors.lastname: Desai
authors.forename: R M
authors.initials: RM
authors.lastname: Love
authors.forename: A M
authors.initials: AM
authors.lastname: Rich
authors.forename: G J
authors.initials: GJ
authors.lastname: Seymour
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies; D018941:Antigens, CD19 / Q000032:analysis; D058070:Asymptomatic Diseases; D001402:B-Lymphocytes / Q000473:pathology; D017252:CD3 Complex / Q000032:analysis; D002908:Chronic Disease; D004396:Coloring Agents; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000473:pathology; D008297:Male; D008739:Methyl Green; D008875:Middle Aged; D010484:Periapical Granuloma / Q000276:immunology* / Q000473:pathology; D010950:Plasma Cells / Q000473:pathology; D011754:Pyronine; D011842:Radicular Cyst / Q000276:immunology* / Q000473:pathology; D013601:T-Lymphocytes / Q000473:pathology; D051195:Toll-Like Receptor 2 / Q000032:analysis*; D055815:Young Adult
chemical_list: D000906:Antibodies; D018941:Antigens, CD19; D017252:CD3 Complex; D004396:Coloring Agents; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D008739:Methyl Green; D011754:Pyronine