[1] Univ Cattolica Sacro Cuore, Fdn Policlin A Gemelli, Unita Operat Complessa Pneumol, I-00168 Rome, Italy
[2] Univ Southampton, Natl Inst Hlth Res, Southampton Resp Biomed Res Unit, Southampton, Hants, England
[3] Univ Southampton, Clin & Expt Sci, Southampton, Hants, England
[4] Univ Calif San Francisco, Dept Med, San Francisco, CA USA