Activation of natural killer cell cytotoxicity of human blood monocytes by a low molecular weight component from VISCUM ALBUM extract

Journal/Book: Arzneim.- Forsch./Drug Res. 39 (II) (12), 1580-1585. 1989;

Abstract: Viscum album extracts (Helixor) were investigated for their potency toinfluence natural killer cell (NK) cytotoxicity of human peripheralblood mononuclear cells (PBMC) in vitro. The samples investigated wereunable to enhance NK cytotoxicity in PBMC/tumor cell co-cultures bydirect short-term mediation but NK cytotoxicity of human PBMC wasstrongly stimulated when PBMC were pre-incubated for 72 h with a partlypurified fraction (HM-BP) derived from extracts of V. album mali.Stimulation of NK cytotoxicity was not dependent from age and sex ofPBMC donors and was directed against highly as well as moderatelyNK-sensitive human tumor cells. The responding effector cells wereidentified as monocytes/macrophages and stimulation of the NKcytotoxicity of these cells was not based on increased proliferation.The active component in the HM-BP fraction has a molecular weight ofabout 1000 Da or smaller and correlates with the structural criteria ofan oligosaccharide. The activity was completely abrogated when theactive fraction was treated with endoglycosidase F or alpha-glucosidase.Partial inactivation was observed after treatment with endoglycosidase Dor hemicellulase. Moreover, the active fraction induced a reduction intumor take incidence and tumor development in mice when applied beforeand after tumor challenge. Author.

Keyword(s): ANIMAL

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