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

Abstract 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-lymphocytes 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 + INF γ or IL4 cells (T c 1,T c 2). 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 + -IFN γ 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 + -IFN γ ratio and FEV 1 (% 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 (T c 1/T c 2) characterizes the inflammatory responses of smokers with established COPD.