Ushigome Y, et al. - Researchers conducted a prospective longitudinal study on the frequencies of Tregs, Th17 cells and monocyte subsets after onset of drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DiHS/DRESS) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), and long after their clinical resolutions in order to investigate if the shift from Treg to Th17 could specifically occur during the course of DiHS/DRESS and to elucidate the subsets of monocytes that are involved in the shift. During the clinical course of DiHS/DRESS, a gradual shift from Treg to Th17 cell development was evident. The shift is mediated by the predominance of classical monocytes at the acute stage and alternatively recruited patrolling monocytes at the resolution stage, respectively.