In this study, we aimed to characterize the Th1 and Th17 components in vitiligo, as well as the epidermal Langerhans cell and myeloid dermal dendritic cell populations, which are capable of driving the proliferation of T cells by presenting autoantigens and producing inflammatory cytokines. It has been demonstrated that Langerhans cells and myeloid dermal dendritic cells can stimulate T cells to directly expand Th1, Th2 and Th17 responses. Hence, one can take the view that autoinflammatory or autoimmune responses in the skin can be driven by factors that, in focal skin regions, will activate DCs, which might then activate specific T cell populations in the skin. Although vitiligo does not have any clear signs of clinical inflammation, it has been established that most cases of nonsegmental vitiligo contain a microscopic inflammatory infiltrate. Infiltrating T cells have been found in peri-lesional vitiligo skin, and circulating auto-antibodies and auto-reactive CD8+ cytotoxic T cells that recognize melanocyte antigens were BAY-60-7550 detected in the sera of a high proportion of vitiligo patients. Th1 responses, as characterized by IFN-c, have been established in vitiligo. T cells expanded from peri-lesional vitiligo skin show a predominately type 1 cytokine profile . The treatment of vitiligo by using IFN-c inhibitors has also given positive therapeutic responses. A recent advance in our understanding of T cells in autoimmune diseases has been the identification of the Th17 subset. Th17 cells are a distinct lineage of proinflammatory T helper cells that are induced in the presence of IL-6/IL-21, TGF-? and IL-1? and expanded under the stimulation of IL-23. Th17 cells have attracted wide interest as they have been implicated in many inflammatory diseases that were previously only linked to Th1 responses, including rheumatoid arthritis, psoriasis, multiple sclerosis and Crohn��s disease. However, not all immune disorders or inflammatory diseases involve an active population of Th17 cells. In the skin, for instance, psoriasis contains a prominent Th17 population, but atopic FTY720 purchase dermatitis has a very minimal Th17 component. In vitiligo, there has been very limited data on whether and how Th17 cells participate in the disease pathogenesis. In a recent study, Basak and co-workers endeavored to compare serum levels of IL-17 between healthy control and vitiligo patient groups. They reported decreased serum TGF-? levels in vitiligo patients, but a quantitative comparison of serum IL-17 levels between the healthy control and vitiligo patient groups was lacking. In this study, we provided direct tissue evidence for Th17 involvement in vitiligo, manifested by elevated IL-17A mRNA levels and the presence of IL-17A+ T cells in the leading edge of vitiligo biopsies.