Furthermore, our findings demonstrate that the maternal anti-HBs, even at high concentrations, in infants does not inhibit the long-term immunogenicity of hepatitis B vaccine. Placental transfer of IgG is an active process and requires the binding of maternal IgG and neonatal Fc receptors in the placenta . was analyzed in 63 pairs of anti-HBs positive mothers and their infants. The mothers were 20C36 years of age (mean, 27.22.8). Of these mothers, 41 had been vaccinated against hepatitis B, 21 had not been vaccinated, and the remaining one was uncertain. All of the 21 unvaccinated women were positive for anti-HBc, indicating that they acquired the specific immunity PETCM by resolved HBV infection. All full-term infants were healthy (Apgar scores 8) at birth with body weights 2800C4600 g (mean, 3354.7369.6). The male and female infants were 28 and 35 respectively. Each of the 63 mothers transferred the anti-HBs to her infant because anti-HBs was positive in each cord serum. To analyze the transplacental transfer efficiency, we compared the anti-HBs concentrations between maternal and cord sera. As shown in Table 1, 84.1% of the cord serum samples had higher concentrations than the corresponding maternal sera. Figure 2 shows the significant positive correlation between maternal and cord blood anti-HBs (linear regression analysis, 73.5 mIU/ml, Mann-Whitney U test, PETCM 81.7 mIU/ml, em P /em ?=?0.562). Since the number of infants with high titers ( 1000.0 mIU/ml) of maternal anti-HBs was small (6 infants), follow-up period was relatively short (one and half years), and the drop out rate was high in the prospective cohort (Figure 1A), we considered that data from larger cohort of subjects with longer follow-up period would validate the results of the prospective study. Thus, we further compared the anti-HBs levels in more vaccinated children born to mothers who had high (1000 mIU/ml) and moderate to low (999C10 mIU/ml) anti-HBs or who SDF-5 were absence or almost absence of anti-HBs (0C9.9 mIU/ml) during the pregnancy in a retrospective survey. In the three subgroups, the mothers’ ages at delivery were similar and positive rates of anti-HBc were comparable (Table 3). Table 3 also shows that at around five and half years after completion of the vaccination, the positive rates of anti-HBs in children in these three subgroups were 72.7%, 69.2%, and 63.9% ( em /em 2?=?1.505, em P /em ?=?0.521) respectively, and the GMC titers of anti-HBs in these children were 38.9, 43.9, and 31.7 mIU/ml respectively (Kruskal-Wallis rank-sum test, em /em 2?=?0.630, em P /em ?=?0.726). Table 3 Long-term immune response after vaccination against hepatitis B in children born to mothers with various anti-HBs levels. thead Anti-HBs in mothers during pregnancy PETCM (mIU/ml)Statistical analysis1000 (n?=?88)10C999 (n?=?94) 10 (n?=?61)Method em P /em /thead Maternal age25.223.5324.823.9525.773.23One-way ANOVA test, em F /em ?=?0.7520.282Children’s age6.140.496.040.575.830.67One-way ANOVA test, em F /em ?=?5.0710.007Male/Femal50/3851/4337/24 em /em 2 test, em /em 2?=?0.6180.734Anti-HBc+ No. (%)10 (11.36)11 (11.70)2 (3.28) em /em 2 test, em /em 2?=?3.6440.162Anti-HBs+ No. (%)64 (72.73)65 (69.15)39 (63.93) em /em 2 test, em /em 2?=?1.3050.521Anti-HBs (mIU/ml)a 38.90 (0C15000.0)43.87 (0C5886.9)31.65 (0C12452.9)Kruskal-Wallis rank-sum test, em /em 2?=?0.6300.726 Open in a separate window aAnti-HBs level was expressed in geometric mean concentration followed by minimum and maximum values in parenthesis. Discussion Our study confirms that anti-HBs in pregnant women may efficiently transfer into their fetuses and the maternal anti-HBs in the majority of newborns is higher than that in their mothers. Furthermore, our findings demonstrate that the maternal anti-HBs, even at high concentrations, in infants does not inhibit the long-term immunogenicity of hepatitis B vaccine. Placental transfer of IgG is an active process and requires the binding of maternal IgG and neonatal Fc receptors in the placenta . As a result, the maternal antibodies in full-term newborns are usually higher than those in their mothers . In accordance with this, we found that anti-HBs in most.