Langerhans cells develop from a lymphoid-committed precursor

Langerhans cells (LCs) are specialized dendritic cells (DCs) strategically located in stratified epithelia, such as those of the skin, oral cavity, ph arynx, esophagus,upper airways,urethra,and female reproductive tract, which are exposed to a wide variety of microbial pathogens. LCs play an essentia l role in the induction of T-lymphocyte responses against viruses, bacteria , and parasites that gain access to those epithelial surfaces, due to their high antigen capture and processing potential and their capacity to presen t antigen peptides to T cells on migration to the lymph nodes.(1) Although LCs have been classically considered of myeloid origin, recent reports, whi ch demonstrate the existence of lymphoid DCs derived from multipotent lymph oid precursors devoid of myeloid differentiation potential,(2-5) raise the question of the lymphoid or myeloid origin of LCs. The present study shows that mouse lymphoid-committed CD4(low) precursors, with the capacity to gen erate T cells, B cells, CD8(+) lymphoid DCs, and natural killer cells,(2,6) also generate epidermal LCs on intravenous transfer, supporting the view t hat LCs belong to the lymphoid lineage. (C) 2000 by The American Society of Hematology.