In vitro recovery of Th1/Th2 balance in PBMCs from patients with immune thrombocytopenia through the actions of IL-18BPa/Fc.

To determine the effects of IL-18BPa/Fc on the cytokine production and survival of peripheral blood mononuclear cells (PBMCs) of immune thrombocytopenia (ITP), PBMCs isolated from patients with ITP and healthy donors were treated with or without of IL-18BPa/Fc. The production of IFN-γ, IL-2, tumor necrosis factor (TNF)-α, IL-4, IL-5 and IL-10 was measured by ELISA, and mRNA expression of IFN-γ and IL-18R was evaluated by RT-PCR. Besides, flow cytometric analysis of cell apoptosis was performed by staining with annexin V-FITC/ Propidium Iodide (PI). The proliferation rate of PBMCs was examined by CCK-8 assay. IL-18BPa/Fc at 10 ng/ml significantly stimulated IL-10 secretion from PBMCs in patients with ITP and healthy donors, while it decreased IFN-γ release. Further, IL-18BPa/Fc enhanced dexamethason(DEX) reduction of PHA-induced IFN-γ production by an additional 38.9%(DEX 20 nmol/l) and 49.9%(DEX 50 nmol/l) in ITP patients. Interestingly, the treatment of PBMCs with IL-18BPa/Fc increased the percentage of early apoptotic cells in patients with ITP. In conclusion, IL-18BPa/Fc, via neutralizing the biologic activity of mature IL-18, accelerates lymphocyte apoptosis and downregulates IFN-γ, while permitting the production of Th2 cytokine IL-10. These observations suggest a role of IL-18BPa/Fc in the recovery of Th1/Th2 balance, as well as its therapeutic potential in the treatment of ITP.