Hanaoka H, Nishimoto T, Okazaki Y, et al. - This study was undertaken to investigate the phenotype and function of circulating CD4⁺Foxp3⁺ T cells in patients with systemic lupus erythematosus (SLE). This study enrolled 47 patients with SLE, 31 with organ-specific autoimmune diseases (15 with multiple sclerosis and 16 with primary immune thrombocytopenia), and 19 healthy subjects. Researchers applied peripheral blood mononuclear cells to assess the proportion and phenotype of CD4⁺Foxp3⁺ cells applying multicolor flow cytometry, the status of the Treg-specific demethylated region of the foxp3 gene by methylation-specific polymerase chain reaction, and the immunoregulatory function of CD4⁺CD25⁺ cells by allogeneic mixed lymphocyte reaction. The results of this study indicate that a unique thymus-derived Treg subset with dichotomic immunoregulatory and T helper 17 phenotypes is elevated in the circulation of SLE patients and may be involved in the pathogenic process of SLE.