Activated regulatory T cells are increased in patients with alopecia areata for suppressing disease acitivity

Alopecia areata is one of refractory inflammatory skin disorders. However the precise mechanism remains obscure and appropriate treatment for severe cases should be developed even patients experience self-regression. We previously evaluated the number of circulating CD4+ CD 25+ regulatory T cells were increased substantially, but not statistically significant in alopecia patients compared with healthy controls (4.69 ± 1.24% vs. 3.81 ± 1.12%, p = 0.074). In the present study, we examined three distinct Treg subsets: activated Treg (aTreg), resting Treg (rTreg), and non-suppressive T cells (non-Treg). aTreg have the strongest suppressive activity among the three subsets and rTreg are moderately suppressive. We examined these subsets from the peripheral blood in 12 alopecia areata and 7 atopic dermatitis patients. aTreg levels and aTreg + rTreg levels of alopecia areata were significantly higher than those of healthy controls (n = 11) (aTreg: 1.87 ± 1.27% vs. 0.92 ± 0.44%, p = 0.022; aTreg + rTreg: 3.22 ± 1.55% vs. 2.38 ± 0.44%, p = 0.045). In the four-group comparison, alopecia areata, atopic dermatitis, psoriasis (n = 15) and healthy controls, aTreg + rTreg levels in alopecia areata tended to be higher among these groups (no significance). aTreg levels in patients not having alopecia total is were significantly higher than that of healthy controls (2.02 ± 0.95% vs. 0.92 ± 0.44%, p = 0.047). aTreg and rTreg levels were negatively correlated with the disease duration (aTreg: r = −0.306; aTreg + rTreg: r = −0.544). These results indicated that increased aTreg + rTreg would suppress the disease activity at early phase and induce spontaneous remission to some extent in alopecia areata patients. Therefore, the maintenance of aTreg levels might prevent the disease progression and be a target of new treatment modality.