Abstract: Objectiv The aim of this study was to investigate the G2D expression of peripheral blood natural killer cells in patients with chronic hepatitis B（CHB）. Methods 20 chronic HBV carriers,18 patients with CHB,16 patients with HBV-induced acute-on-chronic liver failure and 20 healthy individuals were recruited in our hospital between July 2015 and July 2018. The liver biopsies were performed in all patents and normal liver tissue was obtained from the adjacent liver tissues of patients with hepatic hemangioma. Flow cytometry was used to detect NK cells and NKG2D⁺NK cells in peripheral blood,serum perforin and granulase B levels were detected by ELISA,and liver tissue NKG2D mRNA and NKG2D protein expression were detected by fluorescence quantitative PCR and Western bloting,respectively. Results The frequencies of NK cells and NKG2D⁺NK cells in HBV carriers were （5.1±1.5）% and （3.4±1.1）%,in patients with CHB were （8.5±2.0）% and （12.3±2.1）%,in patients with liver failure were （8.8±1.6）% and （19.0±2.4）%,and control were （14.2±2.1）% and （7.5±1.5）% （P<0.05）;serum levels of perforin and granzyme B were （15.2±3.2） ng/L and （23.0±3.5） ng/L,（31.5±3.6） ng/L and （52.5±4.0） ng/L,（60.2±11.0） ng/L and （126.8±30.1） ng/L,and （13.9±4.0） ng/L and （21.1±3.9） ng/L） in the four groups（P<0.05）;the NKG2D mRNA levels and NKG2D protein expression were（0.1±0.0） and （0.0±0.0）,（3.5±0.9） and（1.1±0.2）,（7.0±1.2） and （1.8±0.2）,and （0.6±0.2） and （0.3±0.0） in the four groups （P<0.05）. Conclusion NKG2D might exert its action through the synthesis and secretion of perforin and granulase B by NK cells,and down-regulation of NKG2D might improve liver injury and prevent liver failure.

Key words: Hepatitis B, Acute-on-chronic liver failure, Natural killer cells, NKG2D