Protective effect of a traditional Japanese medicine Hochu-ekki-to (Chinese name : Bu-zhong-yi-qi-tang), on the susceptibility against Listeria monocytogenes in infant mice

In this study, the effect of traditional Japanese (Chinese) medicine, Hochu -ekki-to, HOT (Chinese name: Bu-zhong-yi-qi-tang), on the susceptibility ag ainst Listeria monocytogenes in postneonatal infant mice was examined. Numb ers of bacteria in infant mice (infected at 4 weeks of age) were significan tly higher than those in adult mice (infected at 8 weeks of age) on day 3 ( non-specific resistance phase) and day 5 (specific resistance phase) after infection, Oral administration of 1000 mg/kg of HOT for 7 days to infant mi ce reduced bacterial numbers in the liver and spleen at 5 days after the in fection. The amount of IFN-gamma and the number of IFN-gamma -producing CD4 (+) T cells were lower in infant mice than adult mice but those in infant m ice enhanced by HOT treatment. HOT also enhanced the antigen-presenting fun ction along with the expression of MHC class II in infant macrophages induc ed by heat-killed L. monocytogenes. Further, HOT enhanced the IFN-gamma pro duction from infant CD4(+) T cells independent of the deficiency in the ant igen-presenting function. These findings suggest that HOT induced simultaneously functional maturatio n of both infant antigen-presenting cells and T cells, and consequently dev eloped an anti-listerial Th I response. (C) 2001 Published by Elsevier Scie nce.