Induction of T lymphocyte apoptosis by treatment with glycyrrhizin

The effect of glycyrrhizin (GL), a Chinese herbal drug extracted from licolice roots, on murine lymphocytes for inducing apoptotic cell death was studied. Addition of GL (25-400 mu g/ml) to cultured splenocytes and thymocytes from BALB/c mice definitely promoted DNA fragmentation. A single injection of GL (100 mu g/mouse) into BALB/c mice did not cause any detectable DNA fragmentation or cell death of splenocytes and thymocytes. Cytofluorometric analysis of these cells, however, demonstrated a reduction in mitochondrial transmembrane potentials (Delta Psi m). Repeated injections of GL (100 mu g/mouse/day) into mice for 7 days actually resulted in induction of low grade DNA fragmentation selectively in splenocytes. Cell population analysis of viable lymphocytes suggested that both CD4(+) Th lymphocytes and CD8(+) Tc lymphocytes may have been relatively more sensitive than B220(+) B lymphocytes for the apoptotic cell death. We concluded from these results that GL acts as a rather selective inducer of mature T lymphocyte apoptosis with a reduction in Delta Psi m potentially preceding lymphocyte death.