Cell-type dependence of stability modulation of lectin-initiated contacts by impairment of multivalent carbohydrate binding and intracellular signaling.

Initial ligand selection and the intermolecular spatial arrangement of glycan-lectin complexes are assumed to be essential to induce formation of stable cell aggregates by a lectin. To distinguish effects of these two processes, the tetrameric mistletoe lectin and its isolated B-chain were used. A reduced impact of multivalency for Ehrlich ascites tumor cells in contrast to rat thymocytes was revealed. Signaling is thus initiated in a cell-type-dependent manner. Using selective metabolic inhibitors to reduce signal transfer for aggregate stability, decrease in cellular SH-group level was shown to be a common effect accompanying suppression of lectin-dependent aggregate stability. The results underscore an intrinsic variability in the relative importance of lectin-dependent glycan aggregation on the cell surface for triggering post-binding lectin effects.