sRAGE is a recognized marker of alveolar injury in acute respiratory distress syndrome (ARDS). More recently, it seems to be an interesting marker in asthma. It is the soluble form of the pro-inflammatory RAGE receptor overexpressed in the lungs and in particular the bronchi. It acts as a decoy to its ligands, and thus blocks the pro-inflammatory axis of RAGE. Few studies are available in asthma, especially in children. A local study showed low levels of serum sRAGE in the context of acute bronchiolitis. The same finding emerges from the few studies available in asthma, with rates all the lower when the asthma is poorly controlled. A study carried out in the animal model in 2012 found an absence of inflammatory infiltrate, the absence of increased expression of mucin and the absence of mucus goblet cell hyperplasia within the respiratory epithelium in the absence of RAGE receptor in sensitized mice dust mites, after exposure to their allergen. One could imagine in the long term a potential therapeutic avenue by a substitution in sRAGE in this pathology. The objective of this study is to study the ability of the alveolar sRAGE level measured on broncho-alveolar lavage for assessment, to discriminate the clinical degrees of control of severe asthma in children.