Adhesion of Entamoeba histolytica trophozoites to monolayers of human cells.

The adhesion of radiolabeled trophozoites of Entamoeba histolytica to monolayers of a human intestinal epithelial cell line was found to be dependent on time, temperature, and concentration. Adherence seems to be mediated by a carbohydrate binding protein (lectin), which was previously found in trophozoites of E. histolytica. The adherence of the trophozoites was found to be pH-dependent and was inhibited by several N-acetyl-glucosamine-containing glycoconjugates, such as bacterial peptidoglycan, chitin, and IgA; similar results were obtained with the isolated lectin. Furthermore, the semipurified amoebic lectin and wheat germ agglutinin, which have similar sugar specificities, competed with the intact amoeba for receptor sites on the epithelial cells. In addition, both sera from patients with amoebiasis and an IgG fraction from these sera inhibited lectin activity and the adherence of the trophozoites.