Stimulation of dendritic cell maturation and induction of apoptosis in lymphoma cells by a stable lectin from buckwheat seeds.

ABSTRACT

The present study aims to purify and characterize lectin from tartary buckwheat seeds and study its properties as well as biological activities to determine its possible biomedical applications in promoting maturation and proliferation of peripheral blood DCs derived from healthy donors and to study the effect of inducing apoptosis in human leukemia U937 cells. A novel tartary buckwheat lectin (TBL) protein, purified from tartary buckwheat seeds, showed a single band with a molecular mass of 65 kDa in SDS-PAGE. The purified TBL hemagglutinated both human and animal erythrocytes and showed preference for blood type O and the rabbit blood type. TBL is active at up to 60°C, and it is acid- and alkali-stable. TBL (25 µg/mL) combined with 5 x 10(-5) M rhIL-4 promotes maturation and proliferation of peripheral blood dendritic cells (DCs), which is stronger than that promoted by rhTNF-α (20 ng/mL). Exposure of DCs to 50 µg/mL TBL for 48 h resulted in extensive upregulation of maturation markers CD83 and CD40. These TBL-DCs were capable of producing several pro-inflammatory cytokines such as interleukin-10 (IL-10) and interleukin-12 (IL-12). The results of the treatment of human leukemia U937 cells with TBL in doses of 12.5, 25, 50, and 100 µg/mL showed that tartary buckwheat-derived lectin induces apoptosis in a dose-dependent manner. Our results encourage the use of tartary buckwheat and tartary buckwheat-derived lectins as immunopotentiating foods, targeted to strengthen immune responses and display a potential dietary supplement for cancer prevention.