On the issue of exercise normalcy.

COPD patients. Chest 2007; 132: 156–163. 6 Plumb J, Smyth LJC, Adams HR, et al. Increased T-regulatory cells within lymphocyte follicles in moderate COPD. Eur Respir J 2009; 34: 89–94. 7 Barcelo B, Pons J, Ferrer JM, et al. Phenotypic characterisation of T-lymphocytes in COPD: abnormal CD4+CD25+ regulatory T-lymphocyte response to tobacco smoking. Eur Respir J 2008; 31: 585–562. 8 Lee SH, Goswami S, Grudo A, et al. Antielastin autoimmunity in tobacco smoking-induced emphysema. Nat Med 2007; 13: 567–569. 9 BTS guidelines for the management of chronic obstructive pulmonary disease. The COPD Guidelines Group of the Standards of Care Committee of the BTS. Thorax 1997; 52: Suppl. 5, S1–S28. 10 Pauwels RA, Buist AS, Calverey MA, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2001; 163: 1256–1276. 11 Saetta M, Turato G, Maestrelli P, et al. Cellular and structural bases of chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2002; 163: 1304–1309.