title: Immunohistochemical localization of tissue-type plasminogen activator and type I plasminogen activator inhibitor in radicular cysts.
abstract: BACKGROUND
  The plasminogen/plasmin proteolytic system participates in a wide variety of extracellular matrix degradation. Detailed knowledge of plasminogen activators (PAs) and their inhibitors may be important for understanding the pathogenesis of radicular cysts. The purpose of this study was to investigate the in situ localization of tissue-type PA (t-PA) and type I PA inhibitor (PAI-1) in radicular cysts.
  
  
  METHODS
  Thirty formalin-fixed, paraffin-embedded specimens of radicular cysts were examined using immunohistochemistry. In addition, another section from each radicular cyst specimen was stained with hematoxylin and eosin to assess the presence of inflammatory infiltrates. Differences in t-PA and PAI-1 expression between tissues with low and high levels of inflammation were subsequently analyzed using Fisher's exact test.
  
  
  RESULTS
  Both t-PA- and PAI-1-positive cells were detected in the lining epithelium, connective tissue, inflammatory infiltrates, and endothelium. In addition, the t-PA signal was mainly expressed in epithelial cells. However, the PAI-1 signal was mainly expressed in fibroblasts. Moreover, significantly greater t-PA as well as PAI-1 expression was noted in radicular cysts with high levels of inflammation as compared to tissues with low levels of inflammatory cell infiltrates (P < 0.05).
  
  
  CONCLUSIONS
  The present study confirms earlier indications of local production of PA and its inhibitor in radicular cysts. In addition, this study further shows the tissue localization of the antigens for t-PA as well as PAI-1, and demonstrates that the expression of both t-PA and PAI-1 increases with the grade of inflammation in radicular cysts.
authors.affiliation: Department of Pathology, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Chung-Hung
authors.initials: CH
authors.lastname: Tsai
authors.forename: Sheng-Feng
authors.initials: SF
authors.lastname: Weng
authors.forename: Li-Chiu
authors.initials: LC
authors.lastname: Yang
authors.forename: Fu-Mei
authors.initials: FM
authors.lastname: Huang
authors.forename: Yi-Juai
authors.initials: YJ
authors.lastname: Chen
authors.forename: Yu-Chao
authors.initials: YC
authors.lastname: Chang
mesh_terms: D006801:Humans; D007124:Immunoenzyme Techniques; D017395:Plasminogen Activator Inhibitor 1 / Q000032:analysis / Q000096:biosynthesis*; D011842:Radicular Cyst / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D015842:Serine Proteinase Inhibitors / Q000032:analysis / Q000096:biosynthesis*; D010959:Tissue Plasminogen Activator / Q000032:analysis / Q000096:biosynthesis*
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D015842:Serine Proteinase Inhibitors; D010959:Tissue Plasminogen Activator