The herbal medicine Sho-Saiko-To selectively inhibits CD8+ T-cell proliferation

Sho-saiko-to (SST), a Chinese/Japanese traditional herbal medicine,. has been widely used to treat chronic hepatitis in Japan, and the immunomodulatory proper-ties of SST are likely to mediate its beneficial effect. In the present study, we examined the effects of SST and its various ingredients on the count and proliferation of T-cell subsets in cultured splenocytes and hepatic mononuclear cells. SST. wogonin-7-O-glucuronoside (a major SST ingredient), and wogonin (an intestinal metabolite of wogonin-7-O-glucuronoside) increased CD4/CD8 ratio via a decrease of CD8(+) T-cell counts with no effect on CD4(+) T-cell counts. Flow cytometric analyses of viability. proliferation, and cell cycle revealed that wogonin suppressed CD8(+) T-cell proliferation without inducing cell death. SST and wogonin administered to mice increased the CD4/CD8 ratio in hepatic mononuclear cells but not in splenocytes. These findings suggest that SST may modulate the CD4/CD8 ratio via the selective inhibition of CD8(+) T-cell proliferation by the SST ingredient wogonin-7-O-glucuronoside or its metabolite wogonin. (C) 2004 Elsevier B.V. All rights reserved.