Role of T follicular helper cells and their associated molecules in the pathogenesis of chronic hepatitis B virus infection

In this study, we investigated the roles of T follicular helper (TFH) cells and related molecules in the pathogenesis of chronic hepatitis B virus (HBV) infection. The levels of circulating TFH cells and their surface CD40 ligand (CD40L), as well as CD19(+) B cells and their surface CD40 expression were detected by flow cytometry. Peripheral blood plasma interleukin (IL)-21 levels were detected by enzyme-linked immunosorbent assay (ELISA). Compared with hepatitis B surface antibody (HBsAb)(-) and HBsAb(+) healthy controls, the percentage of TFH cells and their surface CD40L expression significantly increased in patients with chronic HBV infection, particularly those with chronic hepatitis B (P<0.05). The percentage of CD19(+) B cells significantly increased in chronic hepatitis B patients and CD40 expression levels on the CD19(+) B cell surface in chronic HBV infection decreased compared with those in the healthy controls (P<0.05). Compared with the healthy controls, the plasma IL-21 level in chronic hepatitis B patients was significantly increased in chronic HBV carriers and decreased in inactive hepatitis B surface antigen (HBsAg) carriers (P<0.05). The TFH cell percentage, B cell percentage and IL-21 expression did not significantly differ between the hepatitis B e-antigen (HBeAg)(-) and HBeAg(+) chronic hepatitis B groups (P>0.05). The abnormal expression of TFH cells and IL-21 is related to the dysfunction of immune response during chronic HBV infection. The interaction of CD19(+) B cells with TFH cells via their CD40 and CD40L molecules may also play an important role in this process.