Comparative study of the sensitivity of lymphoblastoid and transformed monocytic cell lines to the cytotoxic effects of Viscum album extracts of different origin

Viscum album (VA) preparations consist of aqueous extracts of V. album, the European mistletoe. VA extracts contain mistletoe lectins, which are members of the ribosome-inactivating protein type II family. VA preparations have cytotoxic and immunomodulatory properties. Cytotoxicity induced by VA extracts may differ greatly according to the origin of the preparation (host tree, fermented extract) and the cell type. This work was performed to assess the cytotoxicity of various VA preparations, i.e. VA Qu FrF, Qu Spez, M Spez and VA P, in lymphoblastoid and monocytic cell lines. VA Qu FrF, Qu Spez and M Spez induced dose-dependent cell death and inhibition of cell proliferation in lymphoblastoid T cell lines and in transformed monocytic lines. In contrast, the majority of B cell lines tested were resistant to cytotoxicity induced by VA extracts. While VA Qu FrF, Qu Spez and M Spez were potent inducers of cell death, extracts of VA P, derived from mistletoe plants growing on pine trees, failed to induce any cell death in any of the cell lines examined.