Circulating dendritic cells subsets and CD4+Foxp3+ regulatory T cells in adult patients with chronic ITP before and after treatment with high-dose dexamethasome

Immune thrombocytopenic purpura (ITP) is an autoimmune disorder, and high-dose dexamethasome (HD-DXM) has been used as a first-line therapy for patients with ITP. However, little is known about the role of dendritic cells (DCs) and CD4(+)Foxp3(+) regulatory T (Treg) cells in the pathogenesis of chronic ITP and the effects of HD-DXM on DCs and Treg cells. In this study, we investigated the amounts of circulating myeloid DCs (mDCs), plasmacytoid DCs (pDCs), and CD4(+)Foxp3(+) Treg cells in 26 untreated adult patients with chronic ITP. All patients had thrombocytopenia (platelet count <50 x 10(9)/L) for more than 6 months. We also observed short-time changes of DCs and Treg cells after treatment with HD-DXM in these patients. Both mDCs and pDCs numbers in patients were comparable with that of healthy controls. In contrast, the percentage of Treg cells was significantly reduced in patients when compared with healthy controls (P < 0.0001). After 4-days treatment with HD-DXM, Treg cells and mDCs were increased (P < 0.0001 and P < 0.05), while pDCs decreased (P < 0.0001), and CD11c expression level in mDCs was downregulated (P < 0.0001). These results suggest that Treg cells are deficient in ITP and the immunosuppressive therapy of glucocorticoids could cause the short-time changes of these cells.