Treg analyses. (A) Flow cytometric analysis of Tregs. The representative upper dot-plots are of a healthy control. The suppressive capacity of Tregs in humans seems to be confined to CD4⁺CD25⁺ cells with the highest expression of CD25 (CD4⁺CD25^high) whereas CD4⁺T cell with intermediate expression of CD25 might also contain recently activated T cells without Treg function. However, because of the lack of a defined cut-off for CD25^high expression, the use of this technique does not always offer the reproducible results obtained with the determination of FOXP3-positive cells. The lower plots show the increase of the Treg number following rituximab treatment. Dot plots for CD4⁺Foxp3⁺ Treg cells were gated on CD4⁺CD3⁺ cells. Numbers on plots are percentages of total cells gated within the respective rectangles. (B) Bar histogram showing Treg counts at the various study points. The counts are shown both as absolute concentrations and as percentage of CD4⁺ cells. The numbers above the bars are the mean values. Error bars represent SD. Pre indicates pretreatment; R, responders; and NR, non responders.