DRESS is a drug-induced hypersensivity syndrom that can lead to severe organs failure. The role of cutaneous (c-Eo) and blood eosinophils (b-Eo) in tissue damage remains unknown. We aimed to analyze their activation status in DRESS. We collected retrospectively paraffin-embedded skin biopsies for patients from a French University hospital, who fulfilled criteria for drug-induced maculopapular exanthema (EMP) or DRESS. 1) in 38 patients (18 EMP and 20 DRESS), c-Eo and extracellular eosinophilic granules (ECP, MBP) were identified by immunohistochemical staining and quantified by an original semi-automatic method according to the color deconvolution and circularity parameters. 2) Fluorescence Activated Cell Sorting (FACS) was performed for activation markers of b-Eo in 4 DRESS and 4 healthy subjects. The number of c-Eo was significantly higher in DRESS patients (with anti-MBP staining, p=0,044). Analysis restricted to patients with Eo infiltrate in skin showed that granules were more frequent in the DRESS group according to the number of degranulation areas (p=0,027) and area of degranulation (p=0,02) suggesting that c-Eo from DRESS patients were activated. Analysis of activation markers of b-Eo by FACS showed lower expression of tissue-homing markers like CRTH2 (p=0,018) or activation markers like CD63 (p=0,029) and HLA-DR (p=0,029) in patients with DRESS suggesting a down-regulation of surface markers on b-Eo correlated with their activated status in the skin. Further study will be necessary to better understand the mechanisms of Eo recruitment in DRESS.

« Activation status of cutaneous and blood eosinophils in Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) »