Prospective Registry of Eosinophilia With Respiratory Manifestations With Translational Research Identifying and Characterizing Eosinophils

Introduction: The etiology and therapy of eosinophilic lung diseases are still poorly understood. For individual forms of disease, such as eosinophilic asthma or eosinophilic granulomatosis with polyangiitis (EGPA), new therapeutic approaches exist that block the interleukin IL-5 or the IL-5 receptor. Eosinophilic manifestations of the respiratory tract can exclusively affect the lungs or occur as part of a systemic disease. The manifestations partially overlap and are clinically difficult to differentiate (e.g. eosinophilic asthma, Samter Triad, EGPA or hypereosinophilic syndrome (HES)). It is now known that blood eosinophil counts correlate with the level of eosinophils recruited to the airways. However, it is still unclear whether there is a blood eosinophilia without clinical relevance or whether there is a risk of organ damage (e.g. in HES). Hence, different subtypes of eosinophils