Abstract: BACKGROUND & AIM: This study was designed to elucidate the acute toxicity and immune modulation of Rhubarb ecoction in mice. MATERIAL AND METHODS: LD50 test , The mice were randomly divided into four groups:the negative control,1000mg/kg,2500mg/kg,5000mg/kg, 0.1~0.2ml/10g,1/d,10d, They were fed with various doses of Rhubarb decoction. The complement activities and erythrocyte CR1 adherence function were measured by using trace fast plate complement activity assay and complement activating yeast rosette test, respectively.NK cell activities were measured by improved MTT method.RESULTS:LD50 was about 8043mg/kg.Rhubarb enhance NK cell activities and erythrocyte CR1 adherence function and decrase complement activity. CONCLUSION: Rhubarb enhance cell immunity ,promoting immune cell proliferation ;It activate NK cell activities and Erythrocyte CR1 adherence activity.It assistant therapy as an adjuvant medicine.

Key words: Rhubarb ecoction, complement, Erythrocyte CR1, NK cell