Phenotype and function of circulating memory T cells in human vitiligo*

Vitiligo is a chronic inflammatory skin disorder characterized by the loss of melanocytes. While a T helper cell (Th)1/cytotoxic T cell (Tc)1‐skewed immune response is now well demonstrated in vitiligo, recent data suggest that the T‐cell component could be more complex, involving different combinatorial T‐cell subsets. To analyse the phenotype and function of circulating CD4+ and CD8+ memory T‐cell subsets in patients with stable and active vitiligo, in comparison with patients with psoriasis and healthy controls. This is a monocentric, prospective, descriptive and exploratory study. Multiparametric flow cytometry analyses were performed to evaluate the surface expression of homing and T‐cell‐subset markers together with intracellular cytokine production in peripheral blood mononuclear cells from 60 patients with vitiligo, 25 patients with psoriasis and 28 healthy donors. Vitiligo peripheral blood circulating effector and central memory T cells expressed similar proportions of skin‐homing markers. Decrease in the frequencies of circulating CD4+ and CD8+ Th1/Tc1, Th17/Tc17, and Th1/Th17 or Tc1/Tc17 effector memory T‐cell subsets were observed in patients with vitiligo compared with healthy donors. Similar observations were made in psoriasis. In contrast, vitiligo circulating T cells showed a similar capacity for proinflammatory cytokine production compared with those in psoriasis and healthy controls. The decreased frequencies of circulating Th1/Tc1, Th17/Tc17 and Th1/Th17–Tc1/Tc17 cells suggest a possible migration of these T‐cell subsets into the skin of patients with vitiligo. These could be targeted to prevent flares of the disease. What is already known about this topic? Vitiligo is a chronic inflammatory skin disorder associated with the loss of melanocytes. Vitiligo is characterized by a T helper cell (Th)1/cytotoxic T cell (Tc)1‐skewed immune response in the skin. What does this study add? A thorough analysis of the phenotype and function of circulating memory T cells suggests the migration of Th1/Tc1, Th17/Tc17 and Th1/Th17–Tc1/Tc17 cell subsets in the skin. What is the translational message? A better understanding of the different immune T‐cell subsets involved in vitiligo could lead to better therapeutic options. Linked Comment: Matos. Br J Dermatol 2020; 183:803.