Roles of target cell membrane carbohydrate and lipid in Entamoeba histolytica interaction with mammalian cells

Latex beads and liposomes carrying glycoproteins with carbohydrate sequences recognized by an Entamoeba histolytica galactose-specific binding protein were assessed for their ability to adhere to trophozoites and to stimulate amoeba actin polymerization. Glycoprotein-conjugated beads bound significantly to amoebae but did not stimulate actin polymerization. Glycoprotein-bearing liposomes bound to amoebae and did enhance actin polymerization, as do recognized glycosphingolipid-bearing liposomes (G. B. Bailey, E. D. Nudelman, D. B. Day, C. F. Harper, and J. R. Gilmour, Infect. Immun. 58:43-47, 1990). Liposome-stimulated actin polymerization occurred only if the vesicle contained negatively charged phospholipid. It was concluded that both glycoprotein and glycosphingolipid glycans on the target cell surface are involved in attachment to E. histolytica but do not themselves induce the transmembrane signals that lead to cytoskeleton activation and target destruction. This requires interaction with lipids of the target membrane bilayer.