title: Quantification and location of Chlamydia pneumoniae-specific antigen in the walls of abdominal aortic aneurysms.
abstract: BACKGROUND
  To evaluate the prevalence and quantity of Chlamydia pneumoniae-specific antigen in the three layers (intima, media, and adventitia) of abdominal aortic aneurysms (AAAs), so as to further investigate the pathogenesis of AAAs.
  
  
  METHODS
  Aortic walls were collected from 20 patients with AAA and 11 healthy organ donors. Immunohistochemistry was used to identify the C pneumoniae-specific antigen, and image analysis system was used to quantify and locate it.
  
  
  RESULTS
  The positive rate of C pneumoniae-specific antigen was higher in the AAA group than in the control group (100% vs. 54.54%, p = 0.003), positive intensity decreased from the tunica intima to the adventitia in the AAA group (16.32% ± 2.13%, 14.84% ± 1.80%, and 14.25% ± 1.67%, respectively, p = 0.003). In the control group, positive cells were mainly found in focal lesion areas.
  
  
  CONCLUSIONS
  We have demonstrated the presence and differentiation of C pneumoniae-specific antigen in the three layers of AAAs, which are in accordance with pathology, thus suggesting a pathogenic role of the antigen.
authors.affiliation: Department of Vascular Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xiong
authors.forename: Ji-Chun
authors.initials: JC
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000785:Aneurysm, Infected / Q000382:microbiology*; D000942:Antigens, Bacterial / Q000032:analysis*; D001012:Aorta, Abdominal / Q000382:microbiology*; D017544:Aortic Aneurysm, Abdominal / Q000382:microbiology*; D016022:Case-Control Studies; D002681:China; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D003238:Connective Tissue / Q000382:microbiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D017539:Tunica Intima / Q000382:microbiology; D017540:Tunica Media / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial