Frequency of infiltrating regulatory T-cells in the portal tract of biliary atresia

Purpose Immunological abnormalities have been hypothesized as a pathogenesis of biliary atresia (BA). We previously investigated the frequency and function of circulating regulatory T-cells (Tregs) and reported no differences compared to controls. However, the local Treg profile remains uncertain. We aimed to investigate the frequency of Tregs in BA liver tissues. Methods The number of lymphocytes, CD4 + cells, and CD4 + FOXP3 + Tregs infiltrating the portal tract and the percentage of Tregs among CD4 + cells of BA and control patients were visually counted. The correlation between these data and clinical indicators was also examined. Results The number of lymphocytes, CD4 + cells, and CD4 + FOXP3 + Tregs was higher in the BA group. However, the percentage of Tregs among CD4 + cells was similar in both groups. Each parameter was correlated with serum γ-GTP, but there was no clear association with liver fibrosis, jaundice clearance, and native liver survival. Conclusion The number of Tregs infiltrating the portal tract was higher in BA patients. However, the infiltration of lymphocytes was also generally increased. Tregs appear to be unsuccessful in suppressing progressive inflammation in BA patients, despite recruitment to local sites. Investigation of Treg function in the local environment is warranted.