Origin and Function of Eosinophilic Polynuclear During DRESS Syndrome

Drug Hypersensitivity Syndrome or DRESS for "Drug Reaction with Eosinophilia and Systemic Symptoms" is a serious drug allergy which can be life-threatening for patients with serious organ damage. The pathophysiology of DRESS is still not fully understood. In particular, no study has focused on the characterization of eosinophils, while paradoxically eosinophilia is one of the diagnostic criteria. Likewise, there is no data about the origin of eosinophils and few data are available concerning immune polarization of T-cells or the involvement of innate lymphoid cells type 2 in the recruitment of eosinophils. Our preliminary data on increase activation markers membrane expression of cutaneous eosinophils suggest that this approach could allow the identification of endotypes in which eosinophils are involved and contribute to organ damages. The correlation between tissue infiltration of eosinophils and their degree of activation would then justify the development of targeted therapeutic strategies in DRESS syndrome (anti-IL-5 therapy?). The aim of the project is: 1) Evaluate the activation status of circulating and cutaneous eosinophils in patients with DRESS compared with drug induced maculopapular exanthema without or with eosinophilia (but do not fulfill DRESS criteria) and healthy subjects; 2) Understand the pathophysiological mechanisms at the origin of this eosinophilia.