The study by Schuler and Steinman investigates the properties of murine epidermal Langerhans cells (LC) in vitro and their relationship to dendritic cells (DC) from lymphoid organs. LC, which are minor cell populations in the epidermis, were found to be Ia+ leukocytes derived from bone marrow and capable of presenting antigens to T cells. The authors show that LC undergo a maturation process when cultured for 2-3 days, becoming more potent stimulators of T cell proliferation. Initially, fresh LC are weak stimulators, but their stimulatory capacity increases significantly over time, becoming 3-10 times more active than spleen DC. The maturation process involves changes in morphology, phenotype, and function, including the loss of Birbeck granules and F4/80 antigen, and the acquisition of longer dendrites and increased Ia antigen expression. The study suggests that LC are precursors or immature elements of the DC system, and that their maturation may be influenced by the epidermis.The study by Schuler and Steinman investigates the properties of murine epidermal Langerhans cells (LC) in vitro and their relationship to dendritic cells (DC) from lymphoid organs. LC, which are minor cell populations in the epidermis, were found to be Ia+ leukocytes derived from bone marrow and capable of presenting antigens to T cells. The authors show that LC undergo a maturation process when cultured for 2-3 days, becoming more potent stimulators of T cell proliferation. Initially, fresh LC are weak stimulators, but their stimulatory capacity increases significantly over time, becoming 3-10 times more active than spleen DC. The maturation process involves changes in morphology, phenotype, and function, including the loss of Birbeck granules and F4/80 antigen, and the acquisition of longer dendrites and increased Ia antigen expression. The study suggests that LC are precursors or immature elements of the DC system, and that their maturation may be influenced by the epidermis.