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

Inclusion Criteria for Cases: * The subject has given his/her informed consent and signed the consent form * The subject is affiliated with or beneficiary of a medical insurance system * The subject has had asthma for over a year * The following are present in the patient's medical file: (i) a positive methacholine test (PC20 \< 16 mg/ml) OR (ii) reversibility \> 200 ml and 12% of the FEV1 after inhaling 400 µg or less of a short acting bronchodilator. * Treatment with \>= 1000 µg inhaled beclometasone equivalents Exclusion Criteria for Cases: * The subject is pregnant * The subject is breastfeeding * The subject is participating in another interventional study * The subject has participated in another study in the 3 months preceding inclusion * The subject is in an exclusion period determined by a previous study * The subject is under judicial protection or is an adult under any kind of guardianship * The subject refuses to sign the consent * It is impossible to correctly inform the subject * The subject cannot fluently read French * Chronic respiratory disease present, known or suspected (other than asthma) * Treated with Montelukast Inclusion Criteria for Controls: * The subject has given his/her informed consent and signed the consent form * The subject is affiliated with or beneficiary of a medical insurance system Exclusion Criteria for Controls: * The subject is pregnant * The subject is breastfeeding * The subject is participating in another interventional study * The subject has participated in another study in the 3 months preceding inclusion * The subject is in an exclusion period determined by a previous study * The subject is under judicial protection or is an adult under any kind of guardianship * The subject refuses to sign the consent * It is impossible to correctly inform the subject * The subject cannot fluently read French * Any kind of bronchial problem * Smokers * Chronic respiratory disease present, known or suspected * Treated with Montelukast