Influence of polysaccharides from Viscum album L-on human lymphocytes, monocytes and granulocytes in vitro

Background: An acidic arabinogalactan from European mistletoe (Viscum album L, VAL; 1.34 x 10(6) Dalton) was studied in detail because its immunological properties are poorly characterised. Materials and Methods: Flow cytometric studies focussed on PS-activated proliferation of human lymphocytes measured via incorporation of bromo-deoxyuridine (BrdU), granulocyte phagocytosis via ingestion of FITC-labelled E. coli, and respiratory burst via oxidation of dihydrorhodamine 123 to rhodamine 123. Cytokines were detected in the cell culture supernatants by ELISA. Results; PS, in contrast to mistletoe lectins (ML), significantly stimulated proliferation of CD4(+) T-cells but not CD8(+) and CD19(+) cells. However, ML influenced PS-mediated stimulation wit a synergistic effect in one an dan inhibitory effect in another individual. Furthermore, IN-gamma release was significantly enhanced by PS, favouring a T-helper cell type-1 cytokine pattern, further IL-6 was significantly stimulated, while granulocyte activity was not affected. Conclusions: VAL-PS exert yet unknown stimulatory activities, especially on specific CD4+ T-cells which may be influenced by other extract components like the ML. These components may contribute to the anti-tumour effect of VAL.