Influence of Lewis antigen expression by Helicobacter pylori on bacterial internalization by gastric epithelial cells.

The role of Helicobacter pylori lipopolysaccharide (LPS) Lewis antigens in infection is still not well known. We investigated the influence of Lewis antigen expression by H. pylori on its internalization by AGS cells and the epithelium of human gastric xenografts in nude mice using isogenic mutants in LPS biosynthetic genes. In vivo, colonization rates were unaffected by the change in H. pylori Lewis antigen expression, whereas the number of viable intracellular bacteria was significantly higher with wild-type H. pylori strains expressing Lewis antigens when compared to the isogenic mutants in both models. H. pylori strains expressing more Lewis X antigens (Le(x)) were internalized at a higher rate than those expressing less Le(x), type II Lewis antigens (Le(a) or Le(b)) alone, or no Lewis antigens. Thus, Lewis antigens appear to be involved in the internalization of H. pylori by the gastric epithelium.