Fig. 1

The separation of CD4⁺/CD25⁺/Foxp3⁺ Treg cells into three subpopulations by their cell-surface molecules and in vitro suppressive activity. a Six subsets of CD4⁺ T cells defined by the expression of CD45RA and CD25. b The expression of Foxp3 in each fraction shown in (a). c CD4⁺CD25^++/+++ Tregs in CD4⁺ T cells in HCs and patients with pSS-IP or IPF. d Representative flow cytometric analysis of three subsets of CD4⁺CD25⁺⁺ T cells defined by the expression of CD45RA and CD25. Fraction I: CD45RA⁺/CD25⁺⁺ resting T-regulatory cells (rTregs); Fraction II: CD45RA⁻/CD25⁺⁺⁺ activated T-regulatory cells (aTregs); Fraction III: CD45RA⁻/CD25⁺⁺ cytokine-secreting cells. e–g Percentages of circulating T-regulatory subpopulations (Fr. III, rTreg and aTreg cells) among CD4⁺ T cells in HCs and patients with pSS-IP or IPF. h CFSE-labelled CD4⁺CD25⁻ T cells from HCs were cultured in the presence of soluble CD3 and CD28 either alone or with sorted Treg subpopulations from IPF patients at a 1:2 Treg subpopulations/ CD4⁺CD25⁻ responder cell ratio. The percentages of dividing cells are indicated. SSC: side scatter; CFSE: carboxyfluorescein diacetatesuccinimidyl ester; Responder cells represented CD4⁺/CD25⁻ T cells