Immune responses against Helicobacter pylori in gastric cancer patients and in risk groups for gastric cancer.

Background: It has previously been reported that weak serum IgG but elevated IgA antibody responses against H. pylori may be associated with risk of gastric cancer (GC) development. To search for potential immunologic markers for GC, we analyzed antibody responses against H. pylori in risk groups of cancer development.

Material And Methods: Sera and stomach biopsies collected from H. pylori-infected GC patients as well as from patients with gastric ulcer (GU), atrophic gastritis, intestinal metaplasia (IM) and duodenal ulcer and from H. pylori-infected control subjects without atrophy or IM, and in addition from H. pylori-negative subjects were analyzed for IgG and IgA antibodies against three different H. pylori antigen preparations, that is, membrane protein (MP), urease, and CagA.

Results: We observed an increased serum IgA/IgG titer ratio against H. pylori anti-MP in GC and GU patients, and against CagA in Hp-infected GC patients and risk groups. Female patients with GC had a higher serum anti-MP IgA/IgG titer ratio and a higher proportion of poorly differentiated cancer compared with male patients. As earlier observed, the non-tumorous mucosa of H. pylori-infected GC patients contained considerably lower levels of total IgA and H. pylori-specific IgA compared with H. pylori-infected controls. Similarly, we observed decreased specific mucosal anti-MP IgA response in patients with IM.

Conclusion: We observed several differences in local and systemic immunologic responses against H. pylori in H. pylori-infected GC patients and putative GC risk group patients compared with H. pylori-infected controls. These findings may be of importance in efforts to identify risk groups of GC or early stages of GC.