OBJECTIVETo investigate whether hepatitis B e antigen (HBeAg) can modulate the ability of dendritic cells (DCs) to produce inflammatory cytokines (IL-12/IL-6) upon stimulation in vitro.

METHODSPurified adherent mononuclear cells isolated by Ficoll-hypaque density gradient centrifugation were cultured in complete medium containing granulocyte macrophage colony-stimulating factor plus interleukin (IL)-4 to generate immature (i)DCs. Microscopic analysis and flow cytometry were performed to define the phenotypic characteristics of the iDCs. Then, different concentrations (1, 2 and 5 mug/ml) of HBeAg were added to the culture medium and for 24 hrs of incubation. To induce iDCs' maturation, the various groups of cells were incubated for 24 hrs in differentiation culture with lipopolysaccharide (LPS). Effects on secreted inflammatory cytokines were determined by enzyme-linked immunosorbent assay of the cells' supernatants.

RESULTSAll concentrations of HBeAg led to significant reductions in IL-6 (all P less than 0.05). Similar significant reduction trends were seen for IL-12 at the HBeAg concentrations of 2 and 5 mug/ml (both P less than 0.05), but not at the 1 mug/ml concentration.

CONCLUSIONHBeAg may suppress the production of cytokines from DCs; this mechanism may contribute to the immune escape of HBV that supports persistent infection.