Patient description: A 39-year-old man came to the clinic with cough and shortness of breath that was not relieved by his inhaler. He had these symptoms for 5 days during the past 2 weeks. He doubled his oral corticosteroids in the past week. He is a chef with a history of asthma for 3 years, suffering from frequent cough, wheezing, and shortness of breath and chest tightness. The symptoms become more bothersome within 1-2 hours of starting work every day and worsen throughout the work week. His symptoms improve within 1-2 hours outside the workplace. Spirometry was performed revealing a forced expiratory volume in the first second (FEV1) of 63% of the predicted. His past medical history is significant for seasonal allergic rhinitis in the summer. He doesn't smoke or use illicit drugs. His family history is significant for asthma in his father and sister. He currently uses inhaled corticosteroid (ICS) and fluticasone 500 mcg/salmeterol 50 mcg, one puff twice daily.

Clinical trial eligibility criteria: eligible ages (years): 18.0-75.0,  Asthma Cough (Severe Asthmatics): 1. Ability and willingness to comply with the study procedures 2. Age ≥18 to ≤75 years at the time of informed consent 3. Severe asthma (as defined by GINA step 4/5 classification of asthma severity) after a detailed systematic assessment 4. History of asthma treatment with high doses of Inhaled Corticosteroids (≥1000 µg beclomethasone dipropionate daily, or equivalent) and an additional controller 5. Three patient groups with severe asthma will be investigated in the study and will be defined as follows: T2-High Severe Asthmatics (Group A) Persistent blood eosinophil count ≥0.3x10^9/mL and Persistent high FeNO levels ≥30 ppb and Adherence to inhaled and oral corticosteroid therapy T2-Low Severe Asthmatics (Group B) Persistent blood eosinophil count ≤0.2x10^9/Ml and Persistent low FeNO levels (<30ppb) T2 Intermediate Severe Asthmatics (Group D) Persistent blood eosinophil count ≥ 0.3x10^9/mL OR Persistent FeNO levels ≥ 30 ppb As stated above, these measurements are made at each clinic visit as part of routine care and will be available on all subjects prior to 6. A chest x-ray or CT scan obtained within 12 months before the time of informed consent and showing no new pathology requiring investigation as a potential cause for their cough Mild/moderate severe asthmatics (who have received a diagnosis of asthma from a physician and are defined as step 2/3 using the BTS/SIGN classification of severity and ACQ<1.5) aged 18-75 years inclusive will be recruited from general respiratory clinics in the Belfast HSC Trust. Patients must have the ability and willingness to comply with study procedures  Baseline FEV1 ≤50% of predicted or ≤ 1.0L 2. Asthma exacerbation within 28 days before the time of informed consent or during screening 3. Major episode of infection requiring any of the following Admission to hospital for ≥24 hours within the 28 days before the time of informed consent Treatment with intravenous antibiotics within the 28 days before the time of informed consent or during Screening Treatment with oral antibiotics within the 14 days before the time of informed consent or during Screening 4. For adults: Active tuberculosis (TB) requiring treatment within the 12 months before the time of informed consent (patients are also required to have no recurrence of symptoms in the 12 months following completion of TB treatment), or 5. Known history of severe clinically significant immunodeficiency, including, but not limited to, human immunodeficiency virus infection and/or currently receiving or have historically received intravenous Ig for treatment for immunodeficiency Note: Immunodeficiency encompasses a wide spectrum of human conditions and/or diseases. A relative IgG deficiency that is thought, but not proven, to be a feature of severe asthma would not be exclusionary for the study. 6. Diagnosis or history of malignancy, or current investigation for possible malignancy 7. Other clinically significant medical disease that is uncontrolled despite treatment or that is likely, in the opinion of the investigator, to require a change in therapy or affect the ability to participate in the study 8. History of alcohol, drug, or chemical abuse that would impair or risk the patient's full participation in the study, in the opinion of the investigator 9. Current smoker or former smoker with a smoking history of >15 pack-years A current smoker is defined as someone who has smoked one or more cigarettes per day (or marijuana or pipe or cigar) for ≥30 days within the 24 months before the time of informed consent and for whom cotinine testing is positive. A former smoker is defined as someone who has smoked one or more cigarettes per day (or marijuana or pipe or cigar) for ≥30 days in his or her lifetime (as long as the 30-day total did not the 24 months before the time of informed consent) and for whom cotinine testing is negative. A pack-year is defined as the average number of packs per day times the number of years of smoking. 10. Initiation of or change in allergen immunotherapy within three months before the time of informed consent 11. Treatment with an investigational agent within 30 days of informed consent or 5 half-lives of the investigational agent, whichever is longer 12. Female patients who are pregnant or lactating