Epidermal Langerhans cells are derived from cells originating in bone marrow

Abstract

Langerhans cells constitute a morphologically well characterised subpopulation (3–8%) of mammalian epidermal cells which, in contrast to the bulk of epidermal cells, bear Fc-IgG and C3 receptors¹, express immune response-associated (Ia) antigens and function as antigen-presenting cells and allogeneic stimulatory cells to primed T lymphocytes^2–5. The ontogeny of Langerhans cells has been a subject of considerable debate since their discovery⁶. Although some studies suggest that Langerhans cells are of mesenchymal as opposed to neural or melanocytic origin⁷, direct evidence for this has not been presented. In this study we demonstrate that, after 3 weeks, most of the Langerhans cells (LC) in parental skin which had been transplanted on to F₁ hybrids were of recipient origin whereas keratinocytes remained of donor origin; this indicates that the LC are derived from a mobile pool of cells. Furthermore, in studies of skin from radiation-induced bone marrow chimaeric animals we found that, depending on the strain combination, up to 80% of the epidermal LC were derived from the bone marrow of the donor animals.