Fixed drug eruption: a prototypic disorder mediated by effector memory T cells.

Effector memory T cells are uniquely specialized to mediate protective immunity. However, their excessive activation may result in the development of organ-specific inflammatory diseases, which have not been extensively studied. Fixed drug eruption (FDE), a localized variant of drug-induced dermatoses characterized by relapse in the same location, is a prototypic disorder mediated by excessive activation of effector memory T cells, which are resident in the lesional epidermis. A variety of clinical and pathologic features uniquely observed in FDE lesions can be explained by the presence of CD8(+) intraepidermal T cells with the effector memory phenotype in the FDE lesion. This review focuses on how these T cells are generated, retained in the epidermis, and activated to cause epidermal damage.