Circulating Innate Lymphoid Cell Type 2 (ILC2) Levels and Asthma: a Case-control Study

The secondary objectives of this study are: To show that ILC2 levels differ between asthma patients with a "TH2" (helper T cell type 2) profile and asthma patients with a "non-TH2" profile. A TH2 profile is defined as (for a given patient): * circulating eosinophils \> 500 mm\^3 at least once during the year AND * positive allergy skin or specific IgE (Immunoglobulin E) test AND * induced sputum eosinophil level \>3% of leukocytes AND * exhaled nitric oxide \> 25 ppb. To study the variation in ILC2 levels over time among asthma patients who obtained a good level of control compared to other patients. A good level of control is defined as: * no exacerbations during 6 months of followup (an exacerbation is defined as the un-planned need for care that modifies the patient's prescription for \>48h) * FEV1 (forced expiratory volume in 1 second) value current / FEV1 best value \> 0.8 * symptom levels correspond to an ACQ (Asthma Control Questionnaire) questionnaire score of \< 0.75 over the last 7 days