Inclusion Criteria (healthy subjects):
- Male or female, between 18 and 55 years of age, inclusive.
- no clinically significant abnormalities.
- able to produce an adequate induced sputum sample.
- no history of chronic respiratory disease including asthma.
- no history of allergic symptoms e.g., allergic rhinitis, eczema.
- No other acute illness in the 6 weeks prior to Visit 1.
Additional Inclusion Criterion for Healthy Smoking Subjects
- Be a smoker for >/= 1 year.
Additional Inclusion Criteria (Persistent Asthmatic Subjects):
- No contraindications to the procedures in this study.
- Symptoms compatible with asthma for at least 6 months prior to screening
- Pre-bronchodilator FEV1 >/=50% predicted at Visit 1.
- clinically stable asthma for at least 6 weeks prior to Visit 1.
- No acute illness including asthma exacerbation requiring augmentation of therapy in the 6 weeks prior to Visit 1.
- on current asthma controller therapy for >/= 6 weeks prior to Visit 1.
Additional Inclusion for Steroid Naïve Asthmatics (smoking or non-smoking)
- Must not have received a regular course of inhaled or oral corticosteroids for at least 3 months prior to Visit 1.
Additional Inclusion for Smoking Asthmatics
- Be a smoker for >/= 1 year prior to Visit 1.
Exclusion Criteria (healthy):
- History of any clinically significant medical illness or medical disorders.
- Diagnosis of chronic obstructive pulmonary disease (COPD), cystic fibrosis, or other significant respiratory disorder including significant occupational or environmental exposures with ongoing respiratory symptoms.
- bronchodilator response of >/=12% and at least 200 mL from baseline or an FEV1 value <85% of predicted value at Visit 1.
- positive urine pregnancy screening result.
- recent history (within previous 6 months) of alcohol or drug abuse.
- Positive urine toxicology screen for substances of abuse
- positive serology test for HIV antibodies, hepatitis B surface antigen (HBsAg), or hepatitis C virus antibody (anti-HCV) at Visit 1.
- Received an experimental antibody or biologic therapy within the 6 months prior to Visit 1, or received any other experimental therapy or new investigational agent within 60 days of Visit 1.
- Is an employee or family member of the investigator, study centre or Sponsor.
- Any condition that, in the opinion of the investigator, would complicate or compromise the study, or the well-being of the subject.
- Use of any antioxidants within 1 week of Visit 1 and throughout the study period.
- known allergies, hypersensitivity, or intolerance to short acting β-agonists (SABA).
Additional Exclusion Criterion for Healthy Non-smoking Subjects
- subject is a smoker (regular or irregular), or has smoked or used nicotine-containing products within the 6 months prior to Visit 1.
Additional Exclusion Criteria (Persistent Asthma Subjects):
- Diagnosis of allergic bronchopulmonary aspergillosis (ABPA), allergic bronchopulmonary mycosis (ABPM), or occupational asthma.
- Diagnosis of COPD, cystic fibrosis, or other significant respiratory disorder including significant occupational or environmental exposures with ongoing respiratory symptoms.
- Use of theophylline, N-acetyl cysteine, or any other anti-oxidants within 1 week of Visit 1 and throughout the study period.
- positive test for tuberculosis at Visit 1.
Additional Exclusion Criterion for Non-smoking Asthmatic Subjects
- subject is a smoker (regular or irregular), or has smoked or used nicotine-containing products within the 6 months prior to Visit 1.