circulating innate lymphoid cell type 2 (ilc2) levels and asthma: a case-control study

Conditions: Asthma

Summary: the primary objective of this study is to demonstrate differences in ilc2 blood levels between asthma patients and control patients.

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

Eligibility criteria:
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 \ 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