T cells play an important role in the regulation of the immune response and the prevention of the development of autoimmunity. Over the past 30 years, the development of numerous markers of T cells has allowed the identification and characterization of distinctive T cell subsets that function in unique ways both in the normal immune response and in immune-mediated disease. In this Perspectives Series, recent advances of our understanding of three critical T cell subsets are presented.

Beissert, Schwarz, and Schwarz discuss a subset of T cells that provide critical regulation of many aspects of the immune response, regulatory T cells (Treg). The importance of developing vaccines against new infectious agents as well as numerous cancers has led to a continued interest in the role of cytotoxic T cells in the immune response.

Girardi describes a unique subset of T cells, γδT cells, that are enriched at epithelial surfaces and may play a critical role in both immunoregulation and immunosurveillance.

Andersen and co-authors provide an update on the basic mechanisms of action of cytotoxic T cells and their role in both the pathogenesis and the treatment of disease.

This special web focus, presented by Journal of Investigative Dermatology, highlights some important research pertaining to innate immunity and immune T cells from journals such as Nature, Nature Immunology, Nature Medicine, Nature Reviews Immunology, and Laboratory Investigation.