Tezepelumab and Methacholine Airway Hyperresponsiveness in Participants With Mild Allergic Asthma

Inclusion Criteria: Provision of informed consent prior to any study specific procedures Male and female 18 through 65 years of age Positive skin-prick test to a common aeroallergen Methacholine PD20 ≤ 200mcg Mannitol DRR ≤ 42.3mg/FEV1 %f all (equivalent to PD15 ≤ 635mg) Baseline FEV1 ≥ 70% of the predicted value Negative pregnancy test (urine) for female participants of childbearing potential. Exclusion Criteria: Current or former smoker with >10-pack-year history Current or previous history of lung disease other than mild stable allergic asthma Significant systemic disease, including history of current malignancy or autoimmune disease Involvement in the planning and/or conduct of the study (applies to both Investigator staff and/or staff at the study site) Previous randomisation in the present study. Re-screening (Week -1) for FEV1 and AHR is permitted once for each test. Participation in another clinical study with an investigational product during the last 30 days or 5 half-lives of the drug (whichever is longer) Use of any medications for treatment of asthma other than prophylactic short-acting β2-agonists, or use of short-acting β2-agonists for relief of symptoms less than once weekly. Participants with known hypersensitivity to tezepelumab or any of the excipients of the product. Positive hepatitis C antibody, hepatitis B virus surface antigen or hepatitis B virus core antibody, at screening Known to have tested positive for human immunodeficiency virus Known history of drug or alcohol abuse within 1 year of screening For women only - currently pregnant (confirmed with positive pregnancy test) or breast feeding. Unwillingness or inability to comply with the study protocol for any other reason.