Previous studies have established that dendritic cells trigger an immune response when brought into contact with pathogen-associated antigens. Now, researchers from the University of Minnesota, led by Dr. Daniel Kaplan, have discovered that one particular type of skin-resident dendritic cells, Langerhans cells, directly generate activation of antigen-specific T helper-17 (Th17) cells, one of the key components of immune response, when presented directly with pathogen-associated antigens.
In an article published in Cell, the authors describe three subsets of dendritic skin cells: Langerhans cells (LC), Langerin+ dermal DCs (dDCs), and classic dDCs. Each type of cell was evaluated in the study. While LC was associated with activation of the Th17 cells, cytotoxic lymphocytes (CTLs) were not. The dDCs inhibited the ability of LCs and classic DCs to promote Th17 cell responses; this type of dendritic skin cell was also responsible for the generation of antigen specific CTL and Th1 cells.
Because of their location as one of the first entry points for pathogens into the body, skin-resident dendritic cells are described as “sentries of the immune system” by the authors. Knowing the ways in which these cells deal with pathogen-associated antigens will help researchers understand how the skin can be used for drug delivery and hopefully lead to new treatment options for skin diseases, the researchers write.
"Our work demonstrates that dendritic cells in the skin promote distinct and opposing antigen-specific responses," said Dr. Kaplan. "This has important implications for vaccination strategies that selectively target dendritic cell populations. In addition, the requirement for Langerhans cells in the development of Th17 cells suggests these cells may participate in the early pathogenesis of Th17 cell-mediated skin diseases such as psoriasis."
