Serum antibody response against Helicobacter pylori NCTC 11637 smooth- and rough-lipopolysaccharide phenotypes in patients with H. pylori-related gastropathy

The antigenicity of the Helicobacter pylori lipopolysaccharide (LPS) molecule during the course of natural H. pylori infection in humans was investigated. The IgG and lgA responses against smooth (S)- and rough (R)- form LPS were evaluated in H. pylori positive patients with chronic gastritis (CG, n = 30) and duodenal ulcer disease (DU, n = 16), and in 15 H. pylori- negative dyspeptic subjects. The results demonstrated that anti H. pylori LPS IgG and IgA antibody levels were significantly enhanced in both groups of H. pylori-positive patients compared with H. pylori-negative subjects, thus confirming that H. pylori LPS is part of the immunogenic antigen profile of the bacterium. In addition, a marked response against R-LPS, which significantly correlated with that observed against S-LPS, was found for both IgG and IgA, thus indicating that core oligosaccharide plays a powerful immunogenic role. Since the O-side chain of LPS from H. pylori NCTC 11637 contains epitopes which mimic Lewis x (Le(x)) antigens, the presence of antibodies to monomeric, trimeric, and polymeric Le(x) was also investigated. Antibodies against polymeric Le(x) were detected in two patients suffering from chronic atrophic gastritis and active chronic gastritis, respectively.