In vitro response of stimulated B-CLL lymphocytes of patients treated with Viscum album L. extracts.

Background: Extracts from Viscum album (VA-E) have been shown to induce apoptosis and immunoactivation. To exclude possible B-CLL propagating effects, the in vitro reactions of cultured peripheral blood B-CLL cells were analysed. Patients and Methods: Intracellular expression of apoptosis-associated mitochondrial Apo2.7 and proliferation-associated Ki-67 molecules in B-CLL cells from patients treated with VA-E for 12 months were measured after incubation with various stimuli. Results: Within the observation period, the susceptibility of the B-CLL cells towards the apoptosis-inducing potential of the VA-E significantly decreased. This effect could be due to the presence of physiologically-induced anti-mistletoe lectin antibodies which may block the effects of cytotoxic mistletoe lectins. No significant induction of Ki-67 was observed, but an increase of non-specific binding, even in untreated medium controls, did occur within the last months. Conclusion: In this in vitro setting of the observational study, no stimulation of leukemic cells from the patients treated with VA-E was profound.