Increased ratio of FoxP3+ regulatory T cells/CD3+ T cells in skin lesions in drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms.

BACKGROUND Drug-induced hypersensitivity syndrome/drug rash with eosinophilia with systemic symptoms (DIHS/DRESS) is a severe drug eruption accompanied by multiorgan disorders. Several unique aspects of DIHS/DRESS, including herpesvirus reactivation, liver dysfunction and hypogammaglobulinaemia, have similarities to graft-versus-host disease (GVHD). AIM In this study, we focused on the dynamics of regulatory T cells (Tregs) infiltrating into the skin lesions of DIHS/DRESS and GVHD. METHODS Skin biopsies were taken from patients with DIHS/DRESS, GVHD, or maculopapular drug eruption. Tregs were detected using immunostaining with anti-FoxP3. RESULTS The ratio of FoxP3+ T cells to CD3+ T cells was significantly higher in the skin lesions of patients with DIHS/DRESS than in those of patients with GVHD, and was positively correlated with the number of days from disease onset in the acute phase. CONCLUSIONS The dynamics of Tregs in skin lesions are different between DIHS/DRESS and GVHD, despite there being many similarities between these conditions.