Splenic Treg, B-cell, and plasma-cell levels. After mechanical disruption of the spleen, Tregs were defined on FCM by the phenotype CD4⁺CD25^HighFoxp3⁺, B cells as CD19⁺ lymphocytes, and plasma cells as CD19^LowCD27^High cells. The data are summarized in dot plots representing percentages of B cells (A), plasma cells (B), and Tregs (C) in controls (n = 7), ITP patients not treated with RTX (ITP RTX⁻; n = 8), and ITP patients previously treated with RTX (ITP RTX⁺; n = 10). (D) Foxp3 expression was measured by RT-PCR in sorted splenic CD4⁺ T cells in controls (n = 6), ITP RTX⁻ (n = 4), and ITP RTX⁺ (n = 3). The horizontal bars represent the mean values with standard deviations. *P < .05; **P < .001; ***P < .0001; NS, nonsignificant.