EFFECTS OF GLYCYRRHIZIN ON IMMUNE-MEDIATED CYTOTOXICITY

Intravenous administration of glycyrrhizin is known to decrease elevat ed plasma transaminase levels in patients with chronic viral hepatitis , in which immune-mediated cytotoxicity by cytotoxic T lymphocytes and tumour necrosis factor (TNF)-alpha is considered to play an important pathogenic role. However, the immunological interpretation of the tra nsaminase-lowering action of glycyrrhizin is not known. Studies were p erformed to elucidate this action immunologically by assessing the eff ects of glycyrrhizin on immune-mediated cytotoxicity using an antigen- specific murine CD4(+) T hybridoma line, which exhibits cytotoxicity a gainst antigen-presenting cells after stimulation with specific antige n, and a murine TNF-alpha-sensitive fibroblast line. Glycyrrhizin inhi bited the cytotoxic activity of the T cells against antigen-presenting cells and also suppressed TNF-alpha-induced cytotoxicity in the TNF-a lpha-sensitive cell line in vitro. These results suggest that the decr ease of elevated transaminase levels by glycyrrhizin in patients with chronic viral hepatitis is mediated in part by inhibition of immune-me diated cytotoxicity against hepatocytes.