Regulatory T cells in peripheral blood. (A) Frequency of FOXP3⁺CD25^high cells (gated on CD4⁺ cells) determined by FACS. (B) Absolute number (given as counts per microliter of blood) of CD4⁺FOXP3⁺CD25^high cells determined by FACS. The horizontal lines denote the median values of each group. ***P < .001.