Aim: Recently indoleamine 2,3-dioxygenase (IDO) has drawn considerable attention as a mechanism of immune regulation. Our study was to observe the role of IDO in immune tolerance of chronic hepatitis B (CHB), so as to provide a novel approach for reestablishment of active immunity.
Methods: Peripheral venous blood samples were taken from 50 CHB patients and HBV viral load, T lymphocyte subsets as well as the mRNA, protein and activity of IDO were detected. The correlations between HBV viral load, T lymphocyte subsets and IDO were statistically analyzed. Blood samples from 50 healthy people were tested as a control group.
Results: In CHB patients, the mRNA, protein and activity of IDO were all significantly more than those in control group (mRNA:[2.11 +/- 0.615] x 10(3) vs. [0.143 +/- 0.026] x 10(3); protein: 0.22 +/- 0.06 vs. 0.02 +/- 0.0017; activity: 26.07 +/- 8.12 vs. 4.98 +/- 1.65; P < 0.05) and IDO mRNA was positively correlated with HBV viral load (r = 0.502, P < 0.001) and alanine aminotransferase (ALT) (r = 0.65, P < 0.01). Furthermore, IDO mRNA, protein and activity were negatively correlated with CD4(+) T cells (r = -0.622, -0.682, -0.549 respectively, P < 0.05), CD8 (+) T cells (r = -0.487, -367, -294 respectively, P < 0.05) and the ratio of CD4/CD8 (r = -0.426, -0.533, -0.397 respectively, P < 0.05).
Conclusion: IDO closely correlates with HBV viral load and is responsible for immunotolerance against HBV. Suppression of IDO could be a novel approach to break tolerance in CHB.