Prevalence and specificity of antigastric autoantibodies in adolescents infected with Helicobacter pylori

Objectives: Antigastric autoantibodies (AGA) can be detected in as many as 50% of adults infected with Helicobacter pylori. We investigated H pylori-associated antigastric autoimmunity in children and adolescents. Study design: Patients with dyspepsia (n = 78; mean age 10.9 years, range 2-21 years, SE 0.46 years) underwent gastroscopy. H pylori infection was determined by serologic and histologic features and breath tests. AGA were detected by immunohistochemistry and were characterized by immuno-precipitation with the gastric hydrogen ion, potassium ion, adenosine triphosphatase (H+,K+-ATPase). In absorption assays, antibodies against H pylori were removed to determine the role of molecular mimicry. Results: AGA were detected in 9 (18%) of the 51 infected patients and in 1 (4%) of the 27 noninfected patients (P = .08; nonsignificant) and could not be absorbed to H pylori. Children With AGA were significantly older (P = .01). AGA in H pylori gastritis reacted against the gastric H+,K+-ATPase in 3 (33%) of the 9 patients. Conclusions: The age of the patient or the duration of gastritis seem to be relevant factors for the formation of antigastric autoimununity. The gastric H+,K+-ATPase represents an autoantigen as early as childhood. No evidence for a role of molecular mimicry between H pylori and the host at this young age could be found.