Allergic skin disease: atopic dermatitis as a prototype.

The skin is the largest immune organ in the body. It is strategically positioned as an interface between a hostile antigenic world and a complex immune system characterized by inflammatory cells, mediators, lymphocytes, and a panoply of cytokines. These cytokines act as subcellar messengers that direct effector lymphocytes, eosinophils, mast cells, and a host of other cells to target the skin in allergic inflammation. Just as asthmas and allergic rhinitis are prototypes of IgE-mediated respiratory disease, atopic dermatitis is the prototype allergic skin disease. This article focuses on an understanding of the pathogenic mechanisms involved in atopic dermatitis and outlines the clinical spectrum of cutaneous allergic disease. Finally, a state-of-the-art approach to treatment is offered to the clinician confronted with the management of this difficult disorder.