OBJECTIVETo investigate the mechanisms underlying the ability ofheparin-treated dendritic cells (DCs) to promote Th0 to Th1 differentiation in chronic hepatitis B (CHB).

METHODSPeripheral blood mononuclear cells (PBMCs) were isolated from CHB patients and cultured in RPMI-1640 with recombinant GM-CSF and IL-4 with or without heparin to obtain DCs for study. The levels of Toll-like receptors (TLRs) on the DCs were measured using FACS and qPCR techniques.DC subsets with high expression of TLRs were selected for analysis of functional changes by treatment with the corresponding TLR-siRNA. The CD4+ T cell subpopulation was purified from peripheral blood by Dynal immunomagnetic beads, and then the production of IL-12 by DCs in the presence of poly(I:C) or R848 and ofIFN and IL-4 by Th cells co-cultured with DCs was evaluated by ELISA. The t-test was used for statistical analysis.

RESULTSTLR3 expression, and not expression of TLR 7 or TLR8,was significantly increased in heparin-treated DCs as compared to levels detected in the DCs without heparin treatment (t =2.849,P less than 0.05;t =3.027,P less than 0.05). The level of IL-12 produced by heparin-treated DCs stimulated with poly(I:C) was obviously higher than that produced by DCs without heparin treatment and stimulated with poly(I: C) (t =8.68,P less than 0.01) or with R848 (t =19.01,P less than 0.01). However, the IL-12 production by TLR3-siRNA transfected-DCs was significantly reduced (t =31.49, P less than 0.01).When Th cells from allogenic patients with CHB were co-cultured with the TLR3-siRNA transfectedDCs, the frequency ofCD4+ IFN+ cells was significantly reduced (1.64+/-0.57% vs.6.31+/-0.88%,P less than 0.01),as was the capability of Thl to generate IFNg (t =20.83,Pless than 0.01).

CONCLUSIONHeparin may have up-regulated the TLR3 expression level of DCs, and sequentially promoted Th0 to Th1 differentiation.