ABSTRACT
Foxp3+ natural regulatory T cells (nTreg) play a distinct role in maintaining self tolerance at the pe-riphery. CD25hi and CD127lo were proposed for the identification and purification of nTreg but they have not been confirmed in non-Caucasian populations. This study examined the sensitivity and purity of Foxp3 nTreg identified by CD25 and CD127 in the peripheral blood of Thai subjects (13 males, 15 females with age range of 20-42 years old). The proportions of nTreg/CD4+ as identified by the different markers were as follows: Foxp3+, 18.3 ± 6.4%; CD25hi, 6.4 ± 3.2%; and CD127lo, 54.3 ± 14.2%. Sensitivity tests showed the following results: CD25hi, 23.1%; CD127lo, 40.6%; CD25hiCD127lo, 7.4%. Purity tests concluded as follows: CD25hi, 63.6%; CD25int, 24.9%; CD25lo, 8.7%, CD127lo, 26.5%; CD127hi, 14.9%, and CD25hiCD127lo, 52.0%. In conclusion, the proportions of nTreg in Thai subjects are similar to Caucasian populations. CD25hi is superior to CD127lo for separating Foxp3+ nTreg. Com-bining CD25hi and CD127lo does not improve the nTreg purity Abbreviations: CD25hi, CD25 highly expressed cells; CD25int, CD25 intermediately expressed cells; CD25lo, CD25 low expressed cells; CD127hi, CD127 high expressed cells; CD127lo, CD127 low expressed cells.