FOXP3 and chronic obstructive pulmonary disease: Altered Treg cell numbers have been reported in tobacco use related diseases including increased Treg cell numbers in pulmonary lymphocyte follicles of moderate COPD patients (8), increased Foxp3+ Treg cells in large airways but decreased in small airways (main pathological sites in COPD) (9, 10), and decreased Treg cell numbers in the blood of patients with severe COPD (13), suggesting that the chronic inflammation in these patients may be promoted by lack of this regulatory cell population.