Influence of the galactoside-specific lectin from Viscum album and its subunits on cell aggregation and selected intracellular parameters of rat thymocytes.

Galactose-specific lectin from Viscum album (VAA) was shown to induce the aggregation of rat thymocytes, to increase the intracellular Ca(2+)-availability, and to enhance the menadione-dependent release of H2O2 from cells in a carbohydrate- and dose-dependent manner. This activity was mediated by the carbohydrate-binding B-subunit, whereas the toxic A-subunit failed to display aggregating activity or to affect the intracellular Ca2+. However, incubation of cells in its presence decreased the release of H2O2. These data extend the knowledge of the immunomodulatory potency of VAA, especially its carbohydrate-binding B chain.