Regulatory T cells from active non-segmental vitiligo exhibit lower suppressive ability on CD8+ CLA+ T cells

Background: Recent studies have shown that vitiligo is a T-cell mediated autoimmune disease. Skin-homing cytotoxic T lymphocytes expressing cutaneous lymphocyte-associated antigen (CLA) have been suggested to be responsible for the destruction of melanocytes in vitiligo. An aberration in the suppressive function of regulatory T cells (Tregs) has been reported in vitiligo patients. However, whether the weakened suppressive ability of the Tregs contributes to hyper-activated skin homing CD8(+)CLA(+) T cells remains to be determined. Objectives: To investigate the inhibition of circulating Tregs on the proliferation of autologous CD8(+)CLA(+) T cells in non-segmental vitiligo patients. Methods: CD8(+)CLA(+) T cells and Tregs were obtained from the peripheral blood of 13 non-segmental vitiligo patients and 7 controls. The proliferative responses of CD8(+)CLA(+) T cells were assessed in the absence or presence of autologous Tregs, and the levels of Transforming Growth Factor beta 1(TGF-beta 1) and IL-10 in culture supernatants were detected by enzyme-linked immunosorbent assay. Results: The proliferative responses of circulating CD8(+)CLA(+) T cells in the presence of Tregs were significantly higher in the active vitiligo than in the stable vitiligo and control groups. Tregs from active vitiligo patients exhibited a lower inhibitory effect on proliferation of CD8(+)CLA(+) T cells. The levels of TGF-beta 1 produced by Tregs were significantly lower in active vitiligo than other groups and anti-TGF-beta 1 antibodies could abrogate the suppressive function of Tregs. Conclusions: The functional activity of Tregs is compromised in active vitiligo patients. TGF-beta 1 plays an important role in the autoimmune mechanism of the disease.