[The Langerhans cell. Recent immunologic achievements].

The epidermal Langerhans cells has been keeping, most of its secrets for about a hundred years since its first description in 1868. Its characterization in electron microscopy by Birbeck and then the use of histoenzymology (ATPase) and monoclonal antibodies (against HLA-DR, T6, LCA, C3b...) brought a new great interest on its study. The Langerhans cell must play an important immunologic role in the epidermis because of its responsibility in the antigenic information of the lymphocytes; in this way it may represent the specific epidermal differentiation of the monocyte-macrophage cell type, which are all bone-marrow derived cells. The epidermal Langerhans cell is one of the most important links in the elicitation of contact dermatitis. Recent trends about its metabolism, antigens and functions are reviewed and discussed.