Synergism between lectins and vesicles of Viscum album L.- detection by biochemical and immunological methods

Mistletoe (Viscum album L.) extracts, used in cancer therapy, contain several antitumor and immunologically active ingredients of which the cytotoxic mistletoe lectins and the immunoactive vesicles of chloroplast membranes are particularly important. We have investigated interactions between vesicles and lectins with respect to the question of synergistic or antagonistic effects. First we used biochemical methods. Lectin binding to vesicles was dependent on the pH-value and ionic strength of the buffers used. The strongest interaction was observed at low pH-values and at low ionic strength. Using immunological methods, we found that the combination of lectins and vesicles showed a strong amplifying synergistic effect on the stimulation of lymphocyte proliferation. We found an antagonistic effect in terms of cytotoxicity. In summary, these results demonstrate a significant influence of vesicles on all commonly used methods of determination of mistletoe lectins.