Professional antigen-presenting cells of the skin

The skin functions as an important pro-inflammatory and immune organ. Accordingly, the epidermis and dermis are highly populated by dendritic cells (DC), which are potent antigen-presenting cells (APC) with important immunostimulatory and migratory activities. Whereas the biological characteristics and immunological functions of epidermal DC known as Langernahs cells (LC) have been the focus of intense research in the past, less is known regarding their dermal counterparts named dermal dendritic cells (DDC). Although it has been widely accepted that LC are the more relevant skin-resident APC, recent experimental evidence challenges this concept and proposes a different role for these important cell populations. In this article we compile recent scientific advances regarding the function of different skin-resident DC and we try to reconcile the new observations with the previously established paradigm.