Exclusion criteria
kidney or liver disease, Wheezing, prematurity, congenital lung disease, auto-immune disorders, asthma, wheeze, mental disability
CARDIAC DISEASE, ASTHMA, INFLAMMATORY DISEASE, INFLAMMATORY BOWEL DISEASE

Wheezing children: presence of chronic and/or inflammatory disease other than asthma (e.g. inflammatory bowel disease, auto-immune disorders, cardiac disease, congenital lung disease, kidney or liver disease), prematurity < 35 weeks gestational age, postnatal need for oxygen, CPAP, non-invasive or invasive ventilation, or mental disability.Healthy children: a history of asthma or wheeze, other chronic and/or inflammatory disease other than asthma (e.g. inflammatory bowel disease, auto-immune disorders, cardiac disease, congenital lung disease, kidney or liver disease), prematurity < 35 weeks gestational age, postnatal need for oxygen, CPAP, non-invasive or invasive ventilation or mental disability.Children with a recent course of systemic corticosteroids or antibiotics are not excluded from participation, but the baseline visit will be postponed until at least one month after the treatment.