CD4 and autoimmune thrombocytopenic purpura: Peripheral blood mononuclear cells from ITP patients and controls were stimulated with PMA, ionomycin, and Brefeldin A. The frequencies of CD19+IL-10+ B cells, CD3+CD4+IL-17+ Th17 cells, and CD4+CD25hiFoxp3+ Treg cells were analyzed by flow cytometry.