CD19 and autoimmune thrombocytopenic purpura: The levels of serum IgG (21.33±4.64 g/L, P<0.001) and CD19+ cell percentage(17.27±9.14%, P<0.01) in ITP patients were higher than those in control group (11.15±4.61 g/L, 12.47±2.19%),respectively (Fig 2A).