ACTIVATION OF THE ANTITUMOR EFFECTOR-CELLS BY RADIX BUPLEURI

Radix bupleuri, the root of Bupleuri spp., Chinese medicinal herbs use d for the treatment of influenza, malaria and menstrual disorders, wer e extracted with hot water and separated into five different fractions (RE, RBI, RBII, RBIII and RBIV) by stepwise alcohol precipitation. On e of these fractions, RBI, was then fractionated into RBIa and RBIb by gel filtration using G-100 Sephadex. These two fractions were further purified into RBIai, RBIaii and RBIbi, RBIbii fractions respectively by ion-exchange chromatography using DEAE-Sephadex. Each of these frac tions is a heteropolymer consisting mainly of carbohydrate and varying proportions of protein and uronic acid. RBIaii was found to show stro ng anti-tumor activities in sarcoma-bearing mice. Mechanistic studies showed that RBIaii exhibited a potent activating effect on the cytotox ic activity of macrophages, NK and LAK cells against tumor cells. In a ddition, RBIaii could increase the number of tumor infiltrating lympho cytes (TILs) in the tumor site of WEHI-164-bearing mice. Furthermore, RBIaii could induce the release of interferon-gamma by lymphocytes in vitro.