Chemokine receptor expression defines human Treg cell subsets. (A) Representative flow cytometric analysis of CCR6, CXCR3, CCR4, and CCR10 expression by gated CD4⁺CD45RO⁺CD25⁻ Th cells (top panels) and CD4⁺CD45RO⁺CD25^hiCD127^lo Treg cells (bottom panels) from peripheral blood. (B) Expression of CLA by the indicated Th and Treg cell subsets. Each symbol represents 1 donor; horizontal bars indicate the mean. Data are from 5 donors. (C) Frequency of cells expressing the indicated chemokine receptor combinations among Th and Treg cells. Each symbol represents 1 donor; horizontal bars indicate the mean. Data are from 15 donors.