Biochemistry and Biology of the Langerhans Cell

Abstract

Langerhans cells mainly present in the normal epidermis and are thought to be identical to the proliferating cells in the lesions of histiocytosis-X. The Langerhans cell is positive not only for ATPase, esterase, and acid phosphatase, but also for S-100 protein. Since these findings are similar but distinct from those of monocytes and macrophages, the Langerhans cell may be a cell line independent of the monocyte-macrophage system, designated as T-zone histiocytes. Immunologically, the Langerhans cell has Fc and C3 receptors and Ia-like antigen. Thus, the Langerhans cell may be a member of the immune network, as antigen-presenting cells, in the epidermis. One hypothesis is that Langerhans cells activated by external stimuli induce a local immune reaction by activation and proliferation of T-cells, with the interaction of keratinocytes and macrophages. Because of cytochemical and immunologic similarities between Langerhans cells and histiocytosis-X cells, histiocytosis-X may be a proliferative disorder of immature or neoplastic Langerhans cells.