title: Perforin expression and cytotoxic activity of sputum CD8+ lymphocytes in patients with COPD.
abstract: BACKGROUND
  Previous studies have shown that the inflammatory response to cigarette smoking differs between smokers who acquire COPD and those who do not, and the CD8(+) T- lymphocytes have been identified as a key player in this response.
  
  
  OBJECTIVE
  To investigate the cytotoxic activity and perforin expression of CD8(+) lymphocytes in the airway lumen of patients with COPD.
  
  
  METHODS
  Thirty-six male smokers with COPD, 25 male smokers without COPD, and 10 healthy nonsmokers participated in the study. T-lymphocytes of induced sputum samples were labeled with appropriate monoclonal antibodies and measured using flow cytometry. The cytotoxic activity of CD8(+) cells was defined by incubating them with specific target cells (K562).
  
  
  RESULTS
  The percentage and the total number of CD8(+) lymphocytes were significantly higher in COPD smokers compared to non-COPD smokers (p = 0.01 and p = 0.005, respectively) or to healthy nonsmokers (p = 0.02 and p = 0.01, respectively). Perforin expression in CD8(+) cells was significantly higher in smokers with COPD compared to the other two groups (p = 0.001). Increased cytotoxic activity of T cells was also observed in induced sputum of patients with COPD in comparison to the other two groups.
  
  
  CONCLUSIONS
  CD8(+) cells are not only increased in number in sputum samples of smokers with COPD but are highly activated, expressing high levels of perforin. These findings suggest that CD8(+) T-lymphocytes play a significant role in the inflammatory process of COPD.
authors.affiliation: Department of Thoracic Medicine, University Hospital of Heraklion, Medical School, Crete, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Chrysofakis
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Tzanakis
authors.forename: Despina
authors.initials: D
authors.lastname: Kyriakoy
authors.forename: Maria
authors.initials: M
authors.lastname: Tsoumakidou
authors.forename: Ioanna
authors.initials: I
authors.lastname: Tsiligianni
authors.forename: Maria
authors.initials: M
authors.lastname: Klimathianaki
authors.forename: Nikolaos M
authors.initials: NM
authors.lastname: Siafakas
mesh_terms: D016516:CD4-CD8 Ratio; D002452:Cell Count; D003602:Cytotoxicity, Immunologic; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008875:Middle Aged; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D029424:Pulmonary Disease, Chronic Obstructive / Q000276:immunology*; D012907:Smoking / Q000009:adverse effects / Q000276:immunology; D013183:Sputum / Q000166:cytology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin