Immunohistochemical Findings in Active Vitiligo Including Depigmenting Lesions and Non-Lesional Skin

Background: The evidence that vitiligo is an autoimmune disease is supported by its association with autoimmune conditions, the presence of activated cytotoxic T lymphocytes in the lesions and melanocyte-specific circulating auto-antibodies. Some studies have indicated the normal-appearing skin being immune-targeted for latent melanocyte disappearance. Method: We aimed to characterize immunohistologically the cellular infiltrate and to identify the distribution pattern of T and Langerhans cells (LCs) in the active border of depigmenting lesions and clinically normal skin of 22 patients with progressive non-segmental vitiligo, besides the cellular expression for the cutaneous lymphocyte-associated antigen (CLA), comparing to 10 controls. Results: Immunohistochemical analyses showed an overall reduction of the number of CD1a+ cells, dermal increase of CD8+ T cells, and increase of the epidermal CD3+ T cells number in the active border of lesions. Surprisingly, those cellular changes were also observed in clinically pigmented skin. However, a significant intra-epidermal infiltration of CD8+ T cells was evident only within active border biopsies. The CLA+ cells were not significantly increased in the patients’ skin. Conclusions: The findings of this study suggest an extensively immune-committed skin in active vitiligo, mainly characterized by overall scarcity of CD1a+ cells and dermal increase of CD8+ cells even in apparently normal skin, in addition to the epidermal infiltrate of CD8+ T cells in the depigmenting areas. This report further supports that some CD8+ T and LCs cells play a pivotal role in the process of melanocyte loss, and strengthens an auto-immune hypothesis for vitiligo.