AIM:To determine the relationship between host immunity and the characteristics of viral infection or nucleoside analogues(NAs)themselves in patients with chronic hepatitis B(CHB)receiving NA therapy.METHODS:Fifty-two hepatitis B envelope antigen(HBeAg)positive CHB patients were enrolled and divided equally into two groups.One group received telbivudine(LDT,600 mg/d),and the other group received lamivudine(LAM,100 mg/d).Clinical,virological and immunological parameters were assessed at the baseline and at 4,12,24,36 and 48 wk.RESULTS:Both groups achieved significant hepatitis B virus(HBV)replication inhibition and alanine aminotransferase normalization at 48 wk.At the baseline,compared to healthy controls,CHB patients had a lower circulating CD8 T cell frequency(29.44%±11.55%vs 37.17%±7.30%,p=0.03)and higher frequencies of programmed death 1 positive CD8 T cells(pD-1+CD8 T)(16.48%±10.82%vs 7.02%±3.62%,p=0.0001)and CD4+CD25+Foxp3+T regulatory cells(Tregs)(23.64%±9.38%vs 13.60%±6.06%,p=0.001).On therapy,at the beginning 24 wk with the levels of hepatitis B virus deoxyribonucleic acid(HBV DNA)and HBeAg declining,the frequencies of pD-1+CD8 T cells and Treg cells gradually and significantly declined at 12 and 24 wk in both therapy groups.At treatment week 4,patients treated with LDT had a lower frequency of pD-1+CD8 T cells compared to patients treated with LAM(10.08%±6.83%vs 20.51%±20.96%,p=0.02).The frequency of pD-1+CD8 T cells in all of the CHB patients was significantly correlated with both the HBV DNA level(r=0.45,p=0.01)and HBeAg level(r=0.47,p=0.01)at treatment week 24,but the frequency of Treg cells was only significantly correlated with the HBeAg level(r=0.44,p=0.02).Furthermore,the ability of CD8 T cells to secrete pro-inflammatory cytokines was partially restored after 24 wk of therapy.CONCLUSION:NA-mediated HBV suppression could down-regulate the production of negative regulators of host immunity during the first 24 wk of therapy and could partially restore the ability of CD8 T cells to secrete pro-inflammatory cytokines.This immune modulating response may be correlated with the levels of both HBV DNA and HBeAg. AIM: To determine the relationship between host immunity and the characteristics of viral infection or nucleoside analogues (NAs) themselves in patients with chronic hepatitis B (CHB) receiving NA therapy. METHODS: Fifty-two hepatitis B envelope antigen (HBeAg) positive CHB patients were enrolled and divided equally into two groups. One group received telbivudine (LDT, 600 mg / d), and the other group received lamivudine (LAM, 100 mg / d). Clinical, virological and immunological parameters were assessed at the baseline and at 4,12,24,36 and 48 wk.RESULTS: Both groups achieved significant hepatitis B virus (HBV) replication inhibition and alanine aminotransferase normalization at 48 wk. At the baseline, compared to healthy controls, CHB patients had a lower circulating CD8 T cell frequency (29.44% ± 11.55% vs 37.17% ± 7.30%, p = 0.03) and higher frequencies of programmed death 1 positive CD8 T cells (pD-1 + CD8 T) (16.48% ± 10.82% vs 7.02% ± 3.62% , p = 0.0001) and CD4 + CD25 + Foxp3 + T regulatory cells (Tregs) (23.64% ± 9.38% vs 13.60% ± 6.0 6%, p = 0.001). On therapy, at the beginning 24 wk with the levels of hepatitis B virus deoxyribonucleic acid (HBV DNA) and HBeAg declining, the frequencies of pD-1 + CD8 T cells and Treg cells gradually and significantly At 12 and 24 wk in both therapy groups. At treatment week 4, patients treated with LDT had a lower frequency of pD-1 + CD8 T cells compared to patients treated with LAM (10.08% ± 6.83% vs 20.51% ± 20.96% p = 0.02). The frequency of pD-1 + CD8 T cells in all of the CHB patients was significantly correlated with both the HBV DNA level (r = 0.45, p = 0.01) and HBeAg level ) at treatment week 24, but the frequency of Treg cells was only correlated with the HBeAg level (r = 0.44, p = 0.02) .Furthermore, the ability of CD8 T cells to secrete pro-inflammatory cytokines was partially restored after 24 wk of therapy. CONCLUSION: NA-mediated HBV suppression could down-regulate the production of negative regulators of host immunity during the first 24 wk of therapy and could partially restorethe ability of CD8 T cells to secrete pro-inflammatory cytokines. This immune modulating response may be correlated with the levels of both HBV DNA and HBeAg.