A plant lectin derived from Viscum album induces cytokine gene expression and protein production in cultures of human peripheral blood mononuclear cells.
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 24 h 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)-1 alpha, IL-1 beta, IL-6, tumor necrosis factor-alpha, interferon-gamma, 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-alpha 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-gamma 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 molecules to a higher degree than lymphocytes. Expression of IL-1 beta and IFN-gamma genes could also be observed upon 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.
Hostanska
K
K
Department of Research, University Hospital of Basle, Switzerland.
Hajto
T
T
Spagnoli
G C
GC
Fischer
J
J
Lentzen
H
H
Herrmann
R
R
D002478:Cells, Cultured; D002648:Child; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000378:metabolism*; D014784:Mistletoe / Q000276:immunology*; D028321:Plant Preparations; D010940:Plant Proteins; D010946:Plants, Medicinal; D054790:Ribosome Inactivating Proteins, Type 2; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D014118:Toxins, Biological / Q000096:biosynthesis* / Q000494:pharmacology*
D016207:Cytokines; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C488862:mistletoe lectin I; C009674:ribosome inactivating protein, Viscum