Characteristics of patients from whom sputum was obtained for analysis of inflammatory cell numbers and patients who were unable to produce sputum.

Data are presented as n (%) or median (range), unless otherwise stated. CS: current smoker; F: female; FEV1: forced expiratory volume in one-second; HMW: high-molecular-weight; LMW: low-molecular-weight; M: male; NS: never smoker; NoOA: Non occupational asthma; OA: occupational asthma; PC20: concentration of methacholine inducing a 20% fall in FEV1; SIC: specific inhalation challenge; exS: ex-smoker. ≠ Only patients with PC20 ≤16 mg/mL. *p = 0.009; ** p = 0.033.