Epidermal Langerhans cells bear Fc and C3 receptors

Abstract

THE mammalian epidermis contains a system of dendritic cells, eponymously referred to as Langerhans cells, whose functions are obscure. It is, however, accepted that Langerhans cells are of mesenchymal origin and since they are known also to occur in the dermis, lymph nodes, thymus, and other organs, the concept of Langerhans cells has widened to encompass a cellular system populating the connective tissues and certain stratified squamous epithelia of mammals¹. Among the many hypotheses about their biological significance they have been considered to represent immunocompetent cells or cells which might capture antigenic materials², but there is insufficient evidence for this. Lymphocytes have been observed to be closely associated with Langerhans cells in delayed type hypersensitivity reactions to dinitrochloro-benzene in guinea pigs³; and when guinea pigs passively sensitised with lymphocytes from ferritin-hypersensitive donors, were challenged with ferritin, ferritin-containing Langerhans cells were observed in the draining lymph nodes of the challenged animals⁴. Metals and certain amines have an affinity for Langerhans cells in vitro⁵, but since they can phagocytose ferritin and other substances without previous sensitisation¹, doubt remains whether they are immunologically engaged in the uptake and transport of potentially antigenic material. If Langerhans cells are indeed involved in immunological reactions, they should bear some of the surface markers characteristics of cells with known immunological functions, and we have now shown that they carry receptors for Fc and C3.