Differences in immunological alterations and underlying viral infections in two well-defined severe drug eruptions

Background. Similar drugs (e. g. anticonvulsants) have been implicated in the development of two distinct forms of severe cutaneous drug reactions, Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and drug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS). Aim. To investigate immunological alterations and underlying viral infections that could contribute to the variability in the clinical presentations of these diseases. Methods. We retrospectively analysed clinical variables, serum immunoglobulin levels, numbers of circulating white blood cells, lymphocytes and their subsets, serum levels of several cytokines, and underlying viral infections in both drug reactions, using samples obtained at onset from 9 patients with SJS/TEN and 19 patients with DIHS/DRESS. Results. There were significant differences between the two drug eruptions in the duration of drug intake before onset, the levels of IgG, IgA and IgM, the numbers of circulating white blood cell, lymphocyte, CD3+ T cell and CD8+ T cells, the serum levels of interferon-gamma, and the titres of anti-herpes simplex virus IgG at onset. Conclusions. The difference in the pattern of immune responses shaped in part by previous and underlying viral infections at the time of drug exposure could cause a marked deviation in the pathological phenotype of severe drug eruptions. Elucidating these host factors may provide a basis for therapeutic approaches in patients with severe drug reactions.