RESUMO
<p><b>OBJECTIVE</b>To investigate the role of indoleamine 2,3-dioxygenase (IDO) in immune tolerance in patients with chronic hepatitis B (CHB).</p><p><b>METHODS</b>Peripheral venous blood samples were collected from 50 CHB patients, and HBV viral load, T lymphocyte subsets and of IDO mRNA, protein and activity were detected with the blood samples from 50 healthy donors as the control. The correlations between HBV viral load, T lymphocyte subsets and IDO were statistically analyzed.</p><p><b>RESULTS</b>In CHB patients, the mRNA and protein levels and activity of IDO were all significantly higher than those in control group [mRNA: (2.110-/+0.615)x10(3) vs (0.143-/+0.026)x10(3); protein: 0.22-/+0.06 vs 0.02-/+0.0017; activity: 26.07-/+8.12 vs 4.98-/+1.65; P<0.05]. IDO mRNA level was positively correlated to HBV viral load (r=0.502, P<0.001) and ALT (r=0.65, P<0.01), and IDO mRNA, protein and activity were inversely correlated to CD4+ T cells (r=-0.622, -0.682, and -0.549, respectively, P<0.05), CD8+ T cells (r=-0.487, -367, and -294, respectively, P<0.05) and the ratio of CD4/CD8 (r=-0.426, -0.533, and -0.397, respectively, P<0.05).</p><p><b>CONCLUSION</b>IDO is closely correlated to HBV viral load and responsible for immunotolerance against HBV. Suppression of IDO can be a new therapeutic approach to reverse immunotolerance in CHB.</p>