CD8A and vitiligo: Previous studies have concluded that HO‐1 expression is necessary for Tregs to exert their immunoregulatory function.20, 21 Up‐regulation of HO‐1 activity in vivo can inhibit several immune response, including the proliferation of lymphocytes and cytotoxic immune cells‐mediated cytotoxicity.22, 23 In addition, induction of HO‐1 results in a significant up‐regulation of Foxp3 and TGF‐ß expression.24, 25 Our results showed that HO‐1 markedly enhanced the ability of Tregs to suppress the proliferation of CD8+ T cells in vitiligo.