OBJECTIVETo investigate the change of B-cell activating factor of the TNF family (BAFF) and regulatory T-cells (Tregs) before and after high-dose dexamethasone(HD-DXM) therapy and assess the effect of BAFF on Treg cells in immune thrombocytopenic purpura (ITP).

METHODSThe plasma BAFF concentration was measured by ELISA, and Treg cell numbers by flow cytometry.

RESULTSThe plasma BAFF level \[(599.70 +/- 199.40) pg/ml\] was significantly increased (P < 0.05), and the percentage of Treg cells \[(1.56 +/- 0.73)%\] was significantly decreased (P < 0.01) in ITP patients before treatment as compared with that in controls \[(454.5 +/- 132.5) pg/ml and (4.08 +/- 1.08)%, respectively\]. After treatment with HD-DXM, the plasma BAFF level \[(296.9 +/- 119.7) pg/ml\] was significantly decreased (P < 0.01), and the percentage of Treg cells \[(5.94 +/- 2.22)%\] was significantly increased (P < 0.01). The BAFF level and Treg proportion had no significant correlation with platelets count (P > 0.05). In in vitro assays, no difference was found in the number of Treg cells between rhBAFF0 group and rhBAFF20 group \[(1.53 +/- 0.69)%, (1.49 +/- 0.67)%, P = 0.89)\].

CONCLUSIONBAFF level was increased and Treg cells decreased in ITP patients. HD-DXM might play a role in ITP treatment by down-regulating BAFF expression and up-regulating Treg cells number. BAFF had no influence on the number of Treg cells.