Imbalance between subsets of CD8(+) peripheral blood T cells in patients with chronic obstructive pulmonary disease

Background. CD8(+) T lymphocytes are known to play a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, systematic analyses of CD8(+) T cell (Cytotoxic T cells, Tc) subsets in COPD patients have yet to be well conducted. Methods. The whole Tc subsets, including Tc1/2/10/17, CD8(+) regulatory T cells (Tregs) and CD8(+) α7(+) T cells, were quantified by flow cytometry in peripheral blood from 24 stable COPD subjects (SCOPD), 14 patients during acute exacerbations (AECOPD), and 14 healthy nonsmokers (HN). Results. Acute exacerbations of COPD were accompanied by elevated levels of circulating CD8(+) T cells. Tc1 cells were increased in both SCOPD and AECOPD patients, whereas the percentage of Tc2 cells was decreased in SCOPD patients but remained normal in AECOPD patients. Tc17 cells were increased only in AECOPD patients, and the percentage of Tc10 cells was reduced in both SCOPD and AECOPD patients. The imbalances of pro/anti-inflammatory Tc subsets observed in COPD may be caused by the lack of Tc10 cells and the impaired anti-inflammatory capacity of CD8(+) Tregs. Conclusions. The imbalances between subsets of CD8(+) peripheral blood T cells contribute to the immune response dysfunction in COPD pathogenesis.