Clinical significance of circulating regulatory T Cells, soluble CD25, and CXCL9 in assessing disease activity of vitiligo.

Vitiligo is an autoimmune skin disorder characterized by T-cell-mediated melanocyte destruction and loss of immune tolerance. Dysregulation of regulatory T cells and altered chemokine signaling have been implicated; however, their relationship with disease activity remains unclear. Therefore, this study aimed to evaluate peripheral immune cell subsets, particularly Tregs, sCD25, and CXCL9 biomarkers in patients with vitiligo and their relationship with disease activity. This study included 44 patients with non-segmental vitiligo and 44 matched healthy controls. Peripheral blood lymphocyte subsets and regulatory T cells were analyzed by flow cytometry. Serum CXCL9 and sCD25 were measured by ELISA. Patients were diagnosed with non-segmental vitiligo based on clinical evaluation. Disease severity and activity were assessed using the VASI and VIDA scores. Peripheral lymphocyte subsets were generally preserved; however, CD4⁺ T cells were reduced in patients compared with healthy controls, with a lower CD4/CD8 ratio. Regulatory T cells (CD4⁺CD25⁺FOXP3⁺) were significantly decreased in percentage of patients compared with healthy controls. Treg frequency correlated positively with the VIDA score. Serum CXCL9 and soluble CD25 showed no significant differences between study groups; however, they both correlated inversely with disease activity. Neither marker correlated with the VASI score. Vitiligo is associated with selective immune dysregulation characterized by reduced CD4⁺ T-cell levels and a decreased Treg proportion. Although CXCL9 and sCD25 do not distinguish vitiligo patients from healthy controls, their correlation with disease activity suggests potential utility as dynamic biomarkers.