Abstract: To investigate the effect of HBeAg on immunologic state of neonates and the mechanisms of intra-uterine infection and immunotolerance of hepatitis B virus. Methods 50 neonates delivered by positive HBsAg mothers were divided into the positive HBeAg group and the negative HBeAg group. The serum HBV M and HBV DNA were determined in pregnant women and neonates, also the levels of IFN-γ, IL-2, IL-4 and IL-6 in these neonates and another 20 normal neonates were determined. Results27 pregnant women had positive HBeAg and 23 had negative HBeAg, and of them 22 and 1 neonate had positive HBeAg(P＜0.05) . Compared with the negative HBeAg group (27cases) and the control group，the IL-2 and IFN-γ levels of the positive HBeAg group (23cases) were significantly decreased while the IL-4 and IL-6 levels were significantly increased(P＜0.05)，　but the cytokine levels were not significantly different between the negative HBeAg group and the control group (P＞0.05). ConclusionNeonate HBeAg can be transmitted from positive HBsAg pregnant woman, which may cause an unbalance of the Th1/Th2 cell subset and bring on the immunotolerance of hepatitis B virus, and finally causes intrauterine infection of HBV.

Key words: Hepatitis B e Antigen(HBeAg), vertical transmission, Immune Tolerance