Subpopulations of regulatory T cells in rheumatoid arthritis, systemic lupus erythematosus, and Behcet's disease.

Recently, subpopulations of regulatory T (Treg) cells, resting Treg (rTreg) and activated Treg (aTreg), have been discovered. The authors investigated the relationship between the change of Treg, aTreg and rTreg and autoimmune diseases. Treg cells and those subpopulations were analyzed by using the human regulatory T cell staining kit and CD45RA surface marker for 42 rheumatoid arthritis (RA), 13 systemic lupus sclerosis (SLE), 7 Behcet's disease (BD), and 22 healthy controls. The proportion of Treg cells was significantly lower in RA (3.8% ± 1.0%) (P < 0.001) and BD (3.3% ± 0.5%) (P < 0.01) compared to healthy controls (5.0% ± 1.3%). The proportion of aTreg cells was also significantly lower in RA (0.4% ± 0.2%) (P = 0.008) and BD (0.3% ± 0.1%) (P = 0.013) compared to healthy controls (0.6% ± 0.3%). The rTreg cells showed no significant differences. The ratio of aTreg to rTreg was lower in RA patients (0.4% ± 0.2%) than that in healthy controls (0.7% ± 0.4%) (P = 0.002). This study suggests that the decrement of aTreg not rTreg cells contributes the decrement of total Treg cells in peripheral blood of RA and BD autoimmune diseases. Detailed analysis of Treg subpopulations would be more informative than total Treg cells in investigating mechanism of autoimmune disease.