A plant lectin from Viscum album (ML-I) has been shown to increase the number and cytotoxic activity of natural killer cells and to induce antitumor activity in animal models. However, the mechanisms underlying the effects of ML-I on natural host defenses are unknown. After 24h incubation of peripheral blood mononuclear cells in the presence of 10 and 1 ng/ml of ML-I, mRNA expression and secretion of a panel of cytokines were evaluated by reverse polymerase chain reaction and by ELISA, respectively. The lectin induced expression of interleukin (IL)-1α, IL-1β, IL-6, tumor necrosis factor-α, interferon-γ, granulocyte-monocyte colony-stimulating factor and IL-10 genes but no expression of IL-2 and IL-5 genes could be detected. Regarding cytokine secretion, IL-6 and TNF-α production was induced by 10 ng/ml ML-I. On the other hand, IL-10 secretion was only stimulated by 1 ng/ml lectin. No production of IFN-γ or, as expectable, IL-2 could be detected. In addition, ML-I increased the percentage of HLA-DR+ T lymphocytes in vitro. In tests performed on whole blood, monocytes and granulocytes bound the fluorescence-conjugated ML-I stimulation of nonadherent cells. These results suggest that lectin-sugar interactions on the cell surface of immunocompetent cells can induce cytokine gene expression and protein synthesis.
|Number of pages||10|
|Publication status||Published - Dec 1 1995|
- Tumor necrosis factor-α
- Viscum album
ASJC Scopus subject areas