A VISCUM ALBUM oligosaccharide activating human natural cytotoxicity is an interferon inducer
Journal/Book: Cancer Immunol. Immunother. 32, 222-227. 1990;
Abstract: Commercial Viscum album extract Helixor-M contains a dialysableoligosaccharide (HM-BP) that activates natural killer (NK) cytotoxicityagainst K562 tumour cells when preincubated with human peripheral bloodmononuclear cells (PBMC) for 72 h. The activated effector cells wereexclusively found in the monocyte/macrophage subpopulation. However,when peripheral non-adherent cells (PNAC) were preincubated with HM-BPfor 72 h the NK cytotoxicity of CD56+CD3- NK cells was activated. Thisdiscrepancy was found to be due to the release of prostaglandin E2 fromactivated monocytes/macrophages, which blocked activation of thecytotoxicity of NK cells. Analysis of the supernatant culture mediumafter 72 h preincubation demonstrated that HM-BP induced release ofinterferon gamma (IFN gamma) from T cells (preferentially from CD3+CD4+cells) and of tumour necrosis factor alpha (TNF alpha) frommonocytes/macrophages. Release of IFN gamma was the crucial step foractivation of NK cytotoxicity since enhancement of NK cytotoxicityduring pretreatment of PBMC or PNAC with HM-BP was completely blocked inthe presence of anti-IFN gamma antibodies. Anti-interleukin-2, anti-TNFalpha or anti-IFN alpha antibodies had no effect on the HM-BP-inducedenhancement of NK cytotoxicity. The activation of the NK cytotoxicity ofnonadherent cells by interleukin-2 treatment was found to be synergisticto the enhancement of NK cytotoxicity by treatment with HM-BP. Author.