A plant lectin derived from VISCUM ALBUM induces cytokine gene expression and protein production in cultures of human peripheral blood mononuclear cells

Journal/Book: Natural Immunity 14, 295-304. 1995;

Abstract: A plant lectin from Viscum album (ML-I) has been shown to increase thenumber and cytotoxic activity of natural killer cells and to induceantitumor activity in animal models. However, the mechanisms underlyingthe effects of ML-I on natural host defenses are unknown. After 24 hincubation of peripheral blood mononuclear cells in the presence of 10and 1 ng/ml of ML-I, mRNA expression and secretion of a panel ofcytokines were evaluated by reverse polymerase chain reaction and byELISA, respectively. The lectin induced expression of interleukin (IL)-1alpha, IL-1 beta, IL-6, tumor necrosis factor-alpha, interferon-gamma,granulocyte-monocyte colony-stimulating factor and IL-10 genes but noexpression of IL-2 and IL-5 genes could be detected. Regarding cytokinesecretion, IL-6 and TNF-alpha production was induced by 10 ng/ml ML-I.On the other hand, IL-10 secretion was only stimulated by 1 ng/mllectin. No production of IFN-gamma or, as expectable, IL-2 could bedetected. In addition, ML-I increased the percentage of HLA-DR+ Tlymphocytes in vitro. In tests performed on whole blood, monocytes andgranulocytes bound the fluorescence-conjugated ML-I molecules to ahigher degree than lymphocytes. Expression of IL-1 beta and IFN-gammagenes could also be observed upon ML-I stimulation of nonadherent cells.These results suggest that lectin-sugar interactions on the cell surfaceof immunocompetent cells can induce cytokine gene expression and proteinsynthesis. Author.

Keyword(s): CELLS-CULTURED

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