Immune-Mediated Cytotoxicity に対するグリチルリチンの作用

Abstract

Intravenous administration of glycyrrhizin (GL) is known to decrease elevated plasma transaminase levels in patients with chronic viral hepatits, in which immune-mediated cytotoxicity by cytotoxic T lymphocytes and tumor necrosis factor alpha (TNFα) is considered to play an important pathogenic role. However, im- munological interpretation of the transaminase-lowering action by GL is not clear. Studies were made to elucidate this action immunologically by assessing the effects of GL on immune-mediated cytotoxicity using an antigen specific murine CD4^+ T cell line, which exhibits cytotoxicity against antigen presenting cells (APCs) after stimulation with specific antigen, and two cell lines sensitive to TNFα, a murine fibroblast line and a human hepatoblastoma line. GL suppressed the cytotoxic activity of the T cells against APCs and also inhibited TNFα-induced cytotoxicity in both of these TNFα-sensitive cell lines in vitro. These results suggest that the decrease of elevated transaminase level by GL in patients with chronic viral hepatitis is mediated in part by inhibition of immune-mediated cytotoxicity against hepatocyte.