Anti-Helicobacter pylori antibody response was investigated by means of Western blotting in 76 patients referred for elective upper GI endoscopy. Andibodies against p120 (CagA) antigen were investigated by means of ELISA in 95 patients referred for elective upper gastrointestinal endoscopy. Sensitivity of our own Western blot was 94%, and specificity was 93%. There was a strong correlation between results of Western blotting and ELISA testing. Semi-quantitative evaluation of Western blots was significantly higher in Helicobacter pylori positive persons with antral gastritis (with or without duodenal ulcer) when compared with Helicobacter pylori negative patients. Positive antibody response against p120 (CagA) antigen (> 7.5 U) was found in 37/64 (58%) Hp-positive patients and in 5/31 (16%) currently Hp-negative subjects. Investigation of Helicobacter pylori CagA antigen is important for detailed bacteria description. Evaluation of antibody response against CagA and other immunogenic antigens is significant not only for scientific purpose but has been also clinically relevant. Western blotting provides complex information in this aspect.

        Key words: Helicobacter pylori, anti-body response, CagA,Western blotting.