Drug-induced hypersensitivity syndrome: recent advances in drug allergy

Great strides have been made in the understanding of the pathogenesis and diversity of the clinical symptoms of severe cutaneous adverse drug reactions in the last decade. Among them, drug-induced hypersensitivity syndrome (DiHS) offers a unique opportunity to link between viral infections and the development of severe cutaneous adverse drug reactions, due to its strong association with human herpesvirus 6 infection. This syndrome has several unique features that cannot be solely explained by a drug antigen-driven T-cell activation: they include the delayed onset, paradoxical deterioration of clinical symptoms after withdrawal of the causative drug; unexplained crossreactivity to unrelated multiple drugs; and a variety of long-term sequelae. Dramatic expansions of Tregs observed during the acute stage of DiHS could explain the delayed onset and result in sequential occurrence of viral reactivations. A gradual loss of Treg function occurring after the resolution of DiHS could increase the risk of developin...