Helicobacter pylori, the ulcer pathogen residing in the human stomach, binds to epithelial cells of the gastric antrum. We have examined binding of 13 bacterial isolates to epithelial cell lines by use of a sensitive microtiter plate method in which measurement of bacterial urease activity provides the means for quantitation of bound organisms. Several established human gastrointestinal carcinoma cell lines grown as monolayers were compared for suitability in these assays, and the duodenum-derived cell line HuTu-80 was selected for testing bacterial binding inhibitors. When bacteria are pretreated with oligosaccharides, glycoproteins, and glycolipids, a complex picture of bacterial-epithelial adherence specificities emerges. Among the monovalent inhibitors tested, 3-sialyllactose (NeuAc␣2-3Gal␤1-4Glc; 3SL) was the most active oligosaccharide, inhibiting adherence for recent clinical isolates of H. pylori with a millimolar 50% inhibitory concentration (IC 50). Its ␣2-6 isomer (6SL) was less active. Most of the recent clinical isolates examined were inhibited by sialyllactose, whereas long-passaged isolates were insensitive. Among the long-passaged bacterial strains whose binding was not inhibited by 3SL was the strain ATCC 43504, also known as NCTC 11637 and CCUG 17874, in which the proposed sialyllactose adhesin was recently reported to lack surface expression (

Intravenous alphaGal oligosaccharides, by inhibiting anti-alphaGal antibody activity, delay but do not abolish the onset of HAR.