HBsAg loading on dendritic cells in patients with chronic hepatitis B: expressions of phenotypic molecules.

BACKGROUND: The antigen reducing ability of dendritic cells (DCs), a kind of antigen presenting cells (APCs) initiating immune response, is associated with the specific immune tolerance of chronic hepatitis B (CHB) patients. However, the dysfunction of DCs can be possibly reversed by the stimulation of antigen peptides. In this study, DCs were cultured from peripheral blood monocytes (PBMCs) in patients with CHB in vitro, and the expression of phenotypic molecules on DCs loaded by different concentrations of HBsAg was observed. METHODS: Forty patients with CHB were divided randomly into 4 groups (10 patients in each group). PBMCs were isolated, and DCs were cultured after addition of granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4). On the 9th day, DCs of the experimental groups were loaded at HBsAg concentrations of 2.5 mg/L, 5 mg/L and 10 mg/L for 24 hours, whereas those of the control group were not loaded. An electron microscope was used to analyze the morphological changes of the DCs. The expression of phenotypic molecules on DCs in different groups was detected with flow cytometry. RESULTS: A combination of GM-CSF and IL-4 produced DCs from PBMCs in patients with CHB after being cultured for 9 days, whose morphological changes were tested by an electron microscope. The expression of phenotypic molecules on DCs in the control group was as low as CD83 (8.02+/-3.99)%, CD80 (8.77+/-2.06)%, and MHC-DR (14.05+/-2.66)%. Loaded by different concentrations of HBsAg, the up-regulation of phenotypic molecules on DCs was found, with CD83 (18.35+/-2.93)%, CD80 (42.63+/-7.15)% and MHC-DR (47.49+/-6.59)% in 2.5 mg/L HBsAg loading group, CD83 (17.88+/-3.12)%, CD80 (45.24+/-10.93)% and MHC-DR (47.07+/-8.52)% in 5 mg/L HBsAg loading group and CD83 (16.74+/-2.86)%, CD80 (44.59+/-6.99)% and MHC-DR (48.59+/-7.42)% in 10 mg/L HBsAg loading group, respectively. Compared with the control group, the phenotypic molecules in the experimental groups were all different significantly (P<0.01), but among them, there were no differences (P>0.05). CONCLUSIONS: DCs cultured from PBMCs in the patients with CHB under the conditions of GM-CSF and IL-4 present on the typical dendritic morphology but are immature for expressing low phenotypic molecules. Loaded by different concentrations of HBsAg, the immature DCs can differentiate to mature DCs for expressing increasing phenotypic molecules.