Induced sputum CD8(+) T-lymphocyte subpopulations in chronic obstructive pulmonary disease

Background: Previous studies have shown that the inflammatory response to cigarette smoking differs between smokers who develop chronic obstructive pulmonary disease (COPD) and those who do not and that the CD8(+) T-tymphocytes have been identified as a key player in this process. The aim of this study was to investigate further the role of CD8(+) cells and their subtypes in sputum cells. Methods: Sputum induction was performed in 36 COPD patients, 25 smokers without COPD and 10 non-smoking healthy controls. After stimulation of sputum lymphocytes with phorbol-myristate-acetate, we used double immunocytochemical methods to identify CD4(+), CD8(+) cells and CD8(+) INFgamma or IL4 cells (Tc1, Tc2). Results: COPD patients had an increased number of CD8(+) cells in sputum as compared with smokers without COPD (P = 0.0001) and control subjects (P = 0.001). CD8(+)-IL4 cells were reduced both in COPD and in smokers without COPD compared to controls (P = 0.0001), while CD8(+)-IFNgamma cells were significantly reduced only in COPD (P = 0.001) as compared with controls. A significant (P = 0.02) relationship between the CD8(+)-IL4/CD8(+)-IFNgamma ratio and FEV1 (% pred) was found only in COPD patients. Conclusion: These findings suggest that an imbalance both in T-lymphocyte subpopulation (CD4/CD8) and in CD8(+) cell subsets (Tc1/Tc2) characterizes the inflammatory responses of smokers with established COPD. (C) 2003 Elsevier Ltd. All rights reserved.