[The Langerhans cell: outpost of the immune system in the epidermis].

The Langerhans cell is a dendritic cell within the epidermis, which shows itself as the outer guardian of the immunological system. The cell stretches dendrites between the keratinocytes, makes a spiderweblike antigen snare, and thus plays the part of a highly specialized macrophage within the epidermal tissue. The development of new identification methods has made it possible to study the functions of the Langerhans cell in allergic contact dermatitis. The roll this cell plays in the pathogenesis of other dermatoses is still unclear, however.