ABSTRACT
C ellular and molecular mechanisms underling allergic contact dermatitis (ACD) have been, and still are, under intense investigation, not only for the relevance of ACD in clinical medicine, but also because ACD is a paradigm of T cell-mediated immune reactions of the skin. Epidermal cells are far more than mere spectators of these immune responses, and undergo a functional activation after contact with haptens and subsequently with lymphokines, causing ACD reactions. Keratinocyte activation includes the expression of a plethora of cytokines, chemokines and accessory molecules, which can profoundly influence immunocompetent cells, thereby contributing to the dramatic alterations that occur during ACD. Lastly, activated keratinocytes also produce and become susceptible to immunosuppressive cytokines which can dampen ACD reactions.
