Mistletoe preparations Lectins

Holtskog, R., Sandvig, K. and Olsnes, S. (1988) Characterization of a toxic lectin in Iscador, a mistletoe preparation with alleged cancerostatic properties. Oncology, 45, 172-179. 

The mistletoe lectins inhibited the growth of multidrug-resistant human colon cancer line HT 29 (mdr) in vitro Numerous studies have reported immunostimulatoiy and proapoptotic effects for mistletoe extracts, preparations, and components. The mistletoe extracts and preparations also significantly inhibited carcinogenesis and metastatis. Animal studies have shown that mistletoe preparations suppressed side effects when used as an adjunct to chemotherapy and radiation therapy. ... 

An increase in eosinophil (a type of white blood cell) counts has been reported after administration of lectin-rich European mistletoe preparations (Huber et al. 2005 Stein and Berg 2000). 

In the published trials mistletoe extracts of different origin (host tree) and mode of preparations have been used. Assuming that the lectin VAA-1 is an active component, its content in the extracts varies with the host tree, the season of mistletoe harvest, the extraction procedure, the fermentation, etc. This makes the trials no longer comparable. The demand for future clinical research and trials is the use of biologically active and reproducibly standardized preparations. 

To circumvent the drawbacks of different preparations from plant material, recombinant mistletoe lectin might be the substance of choice. It can be prepared in large quantities of equal quality.The research of the recombinant form of VAA-1 may also give new clinical perspectives. Recent in vitro investigations with recombinant lectin revealed NK stimulatory effects in synergism with IL-2 and IL-12. Similar to plant lectin in animal models, recombinant VAA-1 was also able to stimulate the NK cell-mediated cytotoxic activity of splenocytes Nat 1mm in press Fig. 4). 

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