Mechanisms underlying the activation of cytotoxic function mediated by hepatic lymphocytes following the administration of glycyrrhizin.

Stronger neo-minophagen C (SNMC), a glycyrrhizin (GL) preparation, has been used for the treatment of chronic viral hepatitis. It has been reported that a single administration of SNMC induced the activation of hepatic lymphocytes in number and function in animal studies. However, it is still unknown how SNMC augments the cytotoxic function and why such augmentation of cytotoxicity occurs in the liver and other organs. In this study, SNMC was daily injected into mice (2 mg GL/day/mouse) for 2 weeks. A significant augmentation of cytotoxicity mediated by NK cells, NKT cells and TNFalpha was demonstrated mainly in the liver. The presence of TNFalpha-mediated cytotoxicity in the liver was demonstrated for the first time. In contrast to CD8+ cytotoxic T cells (CD8+ CTL), all these cytotoxicities were preexistent in lymphocytes without the immunization of a specific antigen or alloantigens. NK cytotoxicity was mediated by a perforin system, while NKT cytotoxicity was mediated by a Fas ligand system. The present results suggest that the entire cytotoxic function mediated by hepatic lymphocytes was simultaneously augmented by SNMC.