Role of T cells in atopic dermatitis. New aspects on the dynamics of cytokine production and the contribution of bacterial superantigens.

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease. Influx of activated T cells into the skin lesions represents a hallmark in AD. Recent results indicate a dynamic T-cell-derived cytokine production in AD. In addition to the well-known TH-2 component, chronic lesions and late-phase allergic responses are characterized by an TH-1/TH-0 cytokine pattern. Although there is no doubt that aeroallergens can contribute to the elicitation of acute- and late-phase allergic responses in AD, their role in the immunopathogenesis is controversally discussed. Recent attention has been given to the long-known phenomenon of persistent colonization of AD skin with S. aureus and the potential role of S. aureus-derived superantigens. Evidence from several in vitro and in vivo studies suggests that such bacterial superantigens have the potency to trigger chronic T-cell-mediated skin inflammation. Although these data are certainly suggestive, further clinical studies are required to elucidate the role of bacterial superantigens in initiation, maintenance and, especially, chronicity of skin inflammation.