Evidence for stimulation of tumor proliferation in cell lines and histotypic cultures by clinically relevant low doses of the galactoside-binding mistletoe lectin, a component of proprietary extracts.

The toxic galactoside-specific lectin from mistletoe, a component of proprietary extracts with unproven efficacy in oncology, exhibits capacity to trigger enhanced secretion of proinflammatory cytokines at low doses (ng/ml or ng/kg body weight) and reductions of cell viability with increasing concentrations. To infer any tumor selectivity of this activity, cytofluorimetric and cell growth assays with a variety of established human tumor cell lines were performed. Only quantitative changes were apparent, and the toxicity against tumor cells was within the range of that of the tested fibroblast preparations from 5 donors.

Endogenous lectins as targets for drug delivery.

To minimize side effects of drugs it would be ideal to target them exclusively to those cell types which require treatment. As a means to this end prototypical cellular recognition systems pique our interest to devise biomimetic strategies. Since oligosaccharides of glycoconjugates outmatch other information-carrying biomolecules (proteins, nucleic acids) in theoretical storage capacity by far, work on the sugar code can spark off development of effective targeting devices.

[Immunomodulating mistletoe therapy by lectin standardization: a double-edged sword?].

Taking advantage of an unique, legally generous regulation, proprietary anthroposophic and phytotherapeutic mistletoe preparations are on the market in Germany. One constituent of the extract, the galactoside-specific lectin, is a potent biological response modifier in a very narrow low-dose range. Although the clinical implications of the lectin effects remain to be rigorously defined, this activity already prompted companies to eliminate the common batch-to-batch variations in favor of standardization, keeping the lectin content, which could otherwise vary drastically, purportedly constant.