ACTIVATION OF RETINOIC ACID (RA)-DIFFERENTIATED HL-60 CELLS BY SAPONINS

The effect of saponins on the one of major functions of neutrophil, na mely the generation of superoxide anion (O-2(-)), was investigated usi ng retinoic acid (RA)-differentiated HL-60 cells (promyelocytic leukem ia cells). The generation of O-2(-) from the cells induced by saponins was monitored by the reduction of cytochrome c. All five species of c rude saponins studied here, ie. tea-leaf saponins, tea-seed saponins, ginsenosides, soyasaponins and saikosaponins, stimulated the generatio n of O-2(-) from RA-differentiated HL-60 cells. Tea-leaf saponins show ed the highest stimulating activity, followed by soyasaponins and gins enosides. The cytotoxic activity of saponins was determined by the dye exclusion method after the incubation of RA-differentiated HL-60 cell s with various concentrations of saponins. Saikosaponins and tea-seed saponins exhibited considerable cytotoxic activity and hemolytic activ ity. To examine the involvement of protein kinase C (PKC) in the neutr ophil activation by saponins, the effect of H-7, an antagonist of PKC, on the generation of O-2(-) induced by saponins was investigated. H-7 was found to inhibit the generation of O-2(-) in a dose-dependent man ner, suggesting the participation of PKC in the neutrophil stimulating process by saponins. Tea-leaf saponins, ginsenosides and soyasaponins , which had high neutrophil stimulating activity and low cytotoxic act ivity, seemed to be useful as a biological response modifier (BRM) for the activation of neutrophil.