1 research outputs found
Only αâGal bound to lipids, but not to proteins, is transported across enterocytes as an IgEâreactive molecule that can induce effector cell activation
[Background]: The oligosaccharide galactoseâαâ1,3âgalactose (αâGal), present in mammalian proteins and lipids, causes an unusual delayed allergic reaction 3 to 6 hours after ingestion of mammalian meat in individuals with IgE antibodies against αâGal. To better understand the delayed onset of allergic symptoms and investigate whether proteinâbound or lipidâbound αâGal causes these symptoms, we analyzed the capacity of αâGal conjugated proteins and lipids to cross a monolayer of intestinal cells.[Methods]: Extracts of proteins and lipids from beef were prepared, subjected to in vitro digestions, and added to Cacoâ2 cells grown on permeable supports. The presence of αâGal in the basolateral medium was investigated by immunoblotting, thinâlayer chromatography with immunostaining and ELISA, and its allergenic activity was analyzed in a basophil activation test.[Results]: After addition of beef proteins to the apical side of Cacoâ2 cells, αâGal containing peptides were not detected in the basolateral medium. Those peptides that crossed the Cacoâ2 monolayer did not activate basophils from an αâGal allergic patient. Instead, when Cacoâ2 cells were incubated with lipids extracted from beef, αâGal was detected in the basolateral medium. Furthermore, these αâGal lipids were able to activate the basophils of an αâGal allergic patient in a doseâdependent manner.[Conclusion]: Only αâGal bound to lipids, but not to proteins, is able to cross the intestinal monolayer and trigger an allergic reaction. This suggests that the slower digestion and absorption of lipids might be responsible for the unusual delayed allergic reactions in αâGal allergic patients and identifies glycolipids as potential allergenic molecules.This study was funded by research grant P25868 of the Austrian Science Fund (FWF).Peer reviewe