Airway mucosal inflammation in COPD is similar in smokers and ex-smokers: a pooled analysis
E. Gamble, D. C. Grootendorst, K. Hattotuwa, T. O'Shaughnessy, F. S. F. Ram, Y. Qiu, J. Zhu, A. M. Vignola, C. Kroegel, F. Morell, I. D. Pavord, K. F. Rabe, P. K. Jeffery, N. C. Barnes
European Respiratory Journal Sep 2007, 30 (3) 467-471; DOI: 10.1183/09031936.00013006