Inclusion Criteria for Asthma Participants:
* Age \>18
* Clinical diagnosis of asthma verified by a specialist physician (allergist or pulmonologist) and one or more of the following:
* Historical variability of airflow limitation via classic reversibility criteria (\> 12%, 200 ml within past 10 years).
* Historical methacholine challenge with PC20 \< 8 mg/ml (within past 10 years).
* FEV1 variability, between two clinic visits, of 20% within the past 5 years either with improvement according to appropriate therapy or decrease in lung function upon withdrawal or decrease of therapy.
* Elevated FeNO \> 50 ppb at least once historically (within past 10 years).
* \< 10 pack per year personal tobacco use and not a current smoker of cigarettes or other inhalational tobacco (e-cigarette, marijuana or other inhalational drug use).
* At least partial response of presenting symptoms to GINA Step 1-4 asthma treatment (ICS or ICS/LABA as determined by study physician investigators)
Exclusion criteria for Asthma Participants:
* \>10 pack per year tobacco, current smoker of cigarettes, e-cigarettes or other inhalational drug use.
* Clinically significant lung disease based on imaging or clinical history other than asthma as determined by an allergist or pulmonologist
* Currently pregnant or breastfeeding
* Anemia with hemoglobin level ˂9 mg/dl at the time of study enrollment
Inclusion Criteria for Healthy Controls:
* Age \> 18
* No current smoking (quit \> 6 months previously) confirmed by serum cotinine level \< 1 ng/ml
* \< 10 pack year tobacco history
* No current respiratory symptoms (cough wheeze, dyspnea)
* No current lung disease or other significant medical comorbidity (see exclusion criteria below)
Exclusion Criteria for Healthy Controls:
* Age \< 18
* Diagnosis of asthma, COPD, emphysema, bronchiectasis or other significant lung disease
* Treatment or a history of malignancy currently or within the past 5 years, except completely treated in situ carcinoma of the cervix, completely treated and resolved non-metastatic squamous or basal cell carcinoma of the skin
* Treatment of inflammatory disease or autoimmune disease such as lupus, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis or others
* Treatment with immune modulating medications for a health condition including any of the following (systemic glucocorticoids, sirolimus, tacrolimus, anti-TNF abatacept, azathioprine, methotrexate, cyclosporine, cyclophosphamide, immunoglobulin, mycophenolate, rituximab, plaquenil or others)
* Treatment with anti-IL5, anti-IgE and anti-IL4 receptor alpha for non-asthma indications
* Vaccination within 4 weeks
* History of clinically significant renal, hepatic, cardiovascular, metabolic, neurologic, hematologic, ophthalmologic, gastrointestinal, uncontrolled diabetes, uncontrolled infectious disease, HIV infection, cerebrovascular, or other significant medical illness or disorder which in the judgment of the investigator could impact the participant as a healthy control
* Serum cotinine \> 1 ng/ml
