Skin-homing T cells in cutaneous allergic inflammation.

The involvement of circulating cutaneous lymphocyte-associated (CLA)+ T cells in skin allergy was initially described in atopic and contact dermatitis in a series of experiments performed in Davos, at the Swiss Institute of Allergy and Asthma Research. Since then, numerous studies have confirmed and extended those initial findings. Both basic and clinical research data obtained on this subset of memory T cells support a relevant role of CLA+ T cells in the regional cutaneous immune system. The spectrum of cutaneous diseases where CLA+ T cells have been shown to play a relevant role has expanded far beyond the field of allergy, highlighting the relevance of this memory T-cell subpopulation in cutaneous diseases. The goal of this chapter is to review known features of those cells in atopic dermatitis, contact dermatitis and nonimmediate cutaneous allergic reactions to drugs.