VISCUM ALBUM agglutinin - induced aggregation of blood cells and the lectin effects on neutrophil function

Journal/Book: Biomed. und Pharmacother. 49 (3), 153-158. 1995;

Abstract: Extracts from mistletoe enjoy a large popularity in central Europe as anunconventional treatment modality for cancer, warranting scientificefforts with defined components to delineate any potential benefit. Thegalactose-specific lectin from Viscum album (VAA), known to exhibitimmunomodulatory and ensuing antitumoral capacities in animal modelsystems, was shown to aggregate human blood cells in the followingorder: neutrophils, mononuclear cells--thrombocytes and erythrocytes. Tocontribute to the analysis of lectin effects on individual aspects ofthe host defence system, two parameters of neutrophils werequantitatively assessed, namely the aggregating activity of VAA as ameasure of strength of interaction with cell surface ligands and theeffect of lectin on oxidative metabolism (H2O2 release) of these cells.It was found that whole lectin and its carbohydrate-binding B-subunitpossessed the capacity to induce cell aggregation and H2O2 release,which were blocked by D-galactose and lactose. Both effects displayedsimilar dependence on the lectin concentration in the range 0.1-25micrograms/ml. The toxic A-subunit displayed detectable activity only inhigh doses (50 micrograms/ml) while the bovine heart galaptin (14 kDa;galectin-1) failed to affect neutrophils. The role of oxidativemetabolism in regulation of neutrophil aggregation induced by VAA wasstudied using metabolic inhibitors and controlled heating at 46 degreesC leading to inhibition of plasma membrane NADPH-oxidase system.Trifluoperazine and menadione inhibited the neutrophil aggregation in adose-dependent manner in comparison with such inhibitors as amilorideand theophylline.(ABSTRACT TRUNCATED AT 250 WORDS) Author.

Keyword(s): BLOOD-CELLS/ ME (metabolism)

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