Inhibitory Effects of Ultraviolet B on Human Langerhans Cell Antigen Presenting Function

Ultraviolet B (UVB) radiations are known to suppress induction of cutaneous immune responses. Since these radiations are almost completely absorbed within epidermis, epidermal cells were considered as potential targets for their various effects. Among epidermal cells, interest was focused on Langerhans cells (LC) because these cells are the antigen presenting cell of epidermis and play a key role in contact hypersensitivity reactions. In the murine models, UVB-induced immunosuppression has been described to both direct effect on LC function1 and/or to indirect effect through the liberation of keratinocyte-derived factors2. In human being, only few data are available concerning the mechanisms involved in this process. Here, we analysed the effects of narrow-band of UVB radiation (312 nm) on human LC antigen presenting function by using the mixed epidermal cell lymphocyte reaction (MELR).