Adoptive transfer of mature NK cells decreases the incidence of BA and improves survival, and the level of VP4 in cholangiocytes and the incidence of BA are decreased as the age of mice increases.

<p>(<b>A</b>) The expression of CD69, TNF-α and IFN-γ of NK cells derived from the livers of B6 mice in different age groups was detected by flow cytometry (N = 5) at 24 hours after RRV challenge and the analysis of incidence of BA (N = 11–16). (<b>B</b> and <b>C</b>) RRV challenge was performed in mice of different age groups (N = 5). The protein and mRNA levels of VP4 in the bile ducts were detected by ELISA and realtime RT-PCR at different time points. The values of protein were expressed as mean ng/mg per bile duct weight ± SD. (<b>D</b>) The mRNA levels of HMGB1 in the bile ducts (N = 5 per group) were detected by realtime RT-PCR and are normalized to <i>GAPDH</i>. (<b>E</b>) Histopathological changes of bile ducts in different age groups on different days post-infection. The arrows indicate infiltrated inflammatory cells. The arrow heads indicate injured cholangiocytes. The scale bar = 50 µm. (<b>F</b>) Transferred EGFP-NK cells (white arrows) were found in the liver of recipient newborn B6 mice infected by RRV. The scale bar = 30 µm. (<b>G</b>) The upper panels show gel images representing EGFP mRNA levels in the livers by RT-PCR. The lower panel shows quantitative analysis of EGFP mRNA by realtime RT-PCR. **<i>p</i><0.01. The data of mRNA levels are normalized to <i>β-actin</i>. (<b>H</b>) The summary of distribution of biliary injury grading. Each dot represents an individual mouse pup. The scale bar = 50 µm. (<b>I</b>) Survival analysis of mice subjected to different treatment (N = 8–16). **<i>p</i><0.01.