title: Erythrocyte receptors for cholera and heat-labile enterotoxins of Escherichia coli.
abstract: Many serological reactions using red blood cells (RBC) such as radial immune haemolysis (RIH) and indirect haemagglutination (IH) tests have often been used for the detection of cholera toxin (CT) and heat-labile (LT) enterotoxin produced by porcine and human Escherichia coli strains. In these tests, the enterotoxins bind to sheep, bovine and guinea-pig RBC without any ligand. We studied several factors which might interfere with such binding, as well as the nature of the receptors involved. Treatment of erythrocytes with different enzymes revealed that proteolytic enzymes had no effect on the adsorption of enterotoxins to RBC. Conversely, treatment with neuraminidase increased the adsorption. Experiments carried out with delipidized RBC revealed that none of the enterotoxins under study bound to the cells thus treated. Pre-incubation of ganglioside fractions with the enterotoxins blocked RIH and IH reactions and the biological effect of them on Vero cells. Assaying RBC ganglioside fractions by thin-layer chromatography revealed the presence of GM1. Our results suggest that the receptors for GT and LT enterotoxins in sheep, bovine and guinea pig RBC are gangliosides: mainly GM1.
authors.affiliation: Department of Microbiology and Immunology, University of Campinas, São Paulo, Brazil.
authors.forename: L C
authors.initials: LC
authors.lastname: Ricci
authors.forename: P S
authors.initials: PS
authors.lastname: de Siqueira
authors.forename: W M
authors.initials: WM
authors.lastname: Tamashiro
authors.forename: A F
authors.initials: AF
authors.lastname: de Castro
mesh_terms: D000042:Absorption; D000818:Animals; D002772:Cholera Toxin / Q000493:pharmacokinetics*; D004912:Erythrocytes / Q000032:analysis / Q000201:enzymology / Q000378:metabolism*; D005677:G(M1) Ganglioside / Q000032:analysis / Q000493:pharmacokinetics; D006162:Guanylate Cyclase; D006801:Humans; D011956:Receptors, Cell Surface / Q000378:metabolism*; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D011971:Receptors, Immunologic / Q000378:metabolism*; D018000:Receptors, Peptide; D013552:Swine
chemical_list: D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; C023552:choleragen receptor; D005677:G(M1) Ganglioside; D002772:Cholera Toxin; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled