PP-119 Lamivudine in hepatitis B reactivation in patients with rheumatologic diseases on chronic immunosuppression

investigate the influence of the hepatitis B virus X protein on function of natural killer (NK) cell in NK-92 cells. Methods: The recombinant eukaryotic expression plasmid pcDNA3.1 (+)-HBX was transfected into NK-92 cells with lipofectamine. The expression of HBV X gene was detected by RT-PCR and Western blotting. Western blotting was also applied for the determination of NKG2D level in NK-92 cells. ELISA was employed to determine the IFN-g level secreted by NK-92 cells. And finally the cytotoxicities of NK cells were analyzed by MTT colorimetry, with the hepatoblastoma cell line (HepG2) as target cell. Results: RT-PCR and western blotting confirmed the expression of HBV X gene in the NK-92 cells transfected with pcDNA3.1(+)-HBX. Compare to empty vector transfected and untransfected cells, NKG2D level significantly decreased, cytotoxicity function and IFN-g secretion markedly attenuated in NK-92 cells transfected with cDNA3.1(+)HBX. Conclusions: Transient expression of HBV X gene can decrease IFN-g secretion and cytotoxicities of NK-92 cells. The influence of the hepatitis B virus X protein on cytotoxicities of NK cell was probably associated with downregulation of expression of NKG2D.