Accidental cell death and generation of reactive oxygen intermediates in human lymphocytes induced by thionins from Viscum album L.

The cytotoxic mechanisms of thionins from Viscum album L., the viscotoxins, were investigated in human granulocytes and lymphocytes. The time course o f viscotoxin effects indicate accidental cell death, i.e, membrane permeabi lization, degradation of cytoplasm and chromatin, swelling of mitochondria with loss of their cristae, and generation of reactive oxygen intermediates within 1-2 h, followed by secondary apoptosis-associated events. The visco toxin homologue purothionin from whole-wheat flour and viscotoxin B, howeve r, did not induce cell death in cultured lymphocytes. Cytotoxicity of catio nic and amphipathic viscotoxin was prevented only by cleavage of its disulp hide bridges.