Chronic Obstructive Pulmonary Disease (COPD) is characterized by progressive and irreversible airflow limitation, caused in most cases by cigarette smoking. Increased CD8 cell numbers are associated with disease progression, and the presence of tertiary immune cell follicles in the lungs of COPD patients indicates a possible disease autoimmune component. T regulatory cells (Tregs) play an essential role in the control of adaptive immunity. This article reviews the current understanding of number and location of Tregs in lung compartments (airway lumen, parenchyma and follicles) in COPD patients. Treg lineages are detailed and their potential roles in COPD are considered. We discuss Treg function in COPD patients with a view to explaining the ongoing pulmonary inflammation despite Treg presence
