The therapies (e.g., steroids and B cell depletion) that improve platelet counts also restored the frequency or/and function of regulatory CD4+ T cells in the periphery (67, 163, 166, 169, 173), and the level of circulating TGF-β in ITP patients (170, 171), although it remains to be investigated whether the improvement of regulatory T cells is due to changes in circulating TGF-β (3). This evidence concerns the gene CD4 and autoimmune thrombocytopenic purpura.