Mistletoe (viscum album) lectins as cytokine inducers and immunoadjuvant in tumor therapy. A review.

Therapy of cancer with a Viscum extract has been carried out in Europe for over six decades in thousands of patients with uncertain advantages. This approach has been bedeviled by major problems such as variable composition of the extract, lack of knowledge of active component(s) and mechanism of action, to cite a few. However the recent standardization of Viscumin in terms of galactoside-binding lectin activity has allowed to clarify that it can act as powerful inflammatory mediator able to stimulate the immune system. Merits and demerits of this approach have been reviewed and although the active component has probably not unique immunoenhancing properties, it may be useful as an adjuvant in the biological therapy of cancer and it should not be ignored any longer. As usual, medical progress depends upon experimentation and not exclusively on intuition and emotion.