A novel enzyme immunoassay for serodiagnosis of Helicobacter pylori infection.

Helicobacter pylori has recently been implicated as an etiologic agent of gastroduodenal disorders. Comparing the antibody to H. pylori in the sera of patients with that of normal controls by Western blot analysis, a unique antibody was detected in the sera of patients, which reacted with the 25-kilodalton antigen of H. pylori. On the other hand, monoclonal antibody CP3 prepared in the authors' laboratory also recognized the 25-kilodalton antigen of H. pylori. Whether the serum antibody of the patient recognized the CP3 antigen purified by monoclonal antibody CP3 was then examined. Western blot analysis showed that the patient's serum reacted strongly with the affinity-purified CP3 antigen. Using monoclonal antibody CP3, an enzyme-linked immunosorbent assay to detect CP3 antibody in sera was established. In patients with chronic gastritis and gastric ulcers, the titer of CP3 antibody was significantly higher than in normal controls and correlated with the histological grade of antral gastritis. The detection of CP3 antibody in sera is useful in the diagnosis of chronic gastritis and gastric ulcer associated with H. pylori infection and also in evaluation of the grade of gastritis.