Compared to normal controls, lower percentages of both the CD19+CD24hiCD38hi B cells (8.12 ± 1.21% vs. 2.40 ± 0.62%) and IL-10-producing B cells (6.02 ± 0.44% vs. 2.11 ± 0.35%) were found in B cells from the ITP patient (Figures 1(a) and 1(b), Supplementary 2), revealing the impairment of Bregs in ITP patients. Here, CD19 is linked to autoimmune thrombocytopenic purpura.