The Role of T-Helper 17 Cells and Regulatory T Cells in Acute Diffuse and Total Alopecia: The Increased Function of Regulatory T Cells May Explain the Favorable Prognosis.

BACKGROUND: Acute diffuse and total alopecia (ADTA) is a variant of alopecia areata (AA) that lacks the typical patchy hair loss seen in classical AA and presents with an acute onset of diffuse hair loss. It has a favorable prognosis. OBJECTIVES: The purpose of this study was to assess the role of T-helper (Th) 17 cells and regulatory T cells (Tregs) in the pathogenesis of ADTA and their relevance to the good prognosis of ADTA. METHODS: Twenty-four patients with ADTA and 12 healthy controls were included. Scalp skin samples were obtained for quantitative polymerase chain reaction (qPCR) specific for Th17 cells and Treg-related cytokines. Serum cytokines associated with Th17 cells and Tregs were measured using enzyme-linked immunosorbent assays. Additionally, we performed immunostaining for Th17 cells and Tregs. The correlation of qPCR results, serum cytokine levels, and immunostaining results with clinical characteristics was examined. RESULTS: Lesional IL-2, IL-10, and IL-23A levels were significantly higher in patients with ADTA than in controls. In the progressive stage, lesional IL-2, IL-13, and IL-23A levels were significantly increased compared to those in controls. Serum IL-15 levels were significantly lower in patients than in controls in the progressive stage. In the recovery stage, lesional IL-13 and IL-23A levels were significantly increased compared to those in controls. The ratios of Th17/CD4+ cells and Tregs/CD4+ cells surrounding hair follicles of the patients were 40.73% and 8.50%, respectively, according to immunostaining results. CONCLUSIONS: The increased activity of Treg cells, suggested through IL-10 and IL-15, is a characteristic of ADTA that is distinct from AA. The increased function of Tregs may explain the favorable prognosis of ADTA. Follow-up studies focusing on Tregs, IL-10, and IL-15 are required.