Percentage of CD4⁺CD25⁺CD45RA⁺ and CD4⁺CD25⁺CD45RA^- T cells in peripheral blood of healthy control subjects. PBMCs from 27 healthy donors were stained with CD4, CD25, and CD45RA mAbs. The percentages of CD4⁺CD25⁺CD45RA⁺ and CD4⁺CD25⁺CD45RA^- cells in each individual were calculated using the gating strategy illustrated in panel A. (B) percentages of CD25⁺CD45RA⁺ and CD25⁺CD45RA^- cells within CD4⁺ cells. The total for each individual was calculated by adding the 2 values. Horizontal bars represent the group means. (C-D) CD25⁺CD45RA⁺ cells are shown as a percentage of CD4⁺ cells and of CD4⁺CD45RA⁺ cells, respectively, as a function of age. Exponential decay curves have been fitted to the data.