[Evaluation of western blot methods for serologic diagnosis of Helicobacter pylori infections]

Abstract

Recent studies have demonstrated that immunoblot method is more sensitive and specific than enzyme immunoassays (EIA) to diagnose Helicobacter pylori infections, and it also permits the detection of antibody profiles against different bacterial antigens including the virulence factors. The aim of this study was to evaluate the diagnostic value of Western Blot (WB) method in the serological diagnosis of H. pylori infections. For this purpose, H. pylori IgG and IgA antibodies have been searched qualitatively by a commercial WB test (Euroimmun GmbH, Germany), in the sera of 23 patients (9 female, 14 male) ages between 6-70 years old (13 children, 10 adults), who were diagnosed as H. pylori infection with the positive results of at least three of the conventional methods (culture and polymerase chain reaction of endoscopic biopsy specimens, 13C urea breath test, serum IgG-EIA methods). All of the patients (100%) were found positive by WB-IgG, and 9 (39%) were positive by WB-IgA tests. H.pylori IgG and IgA antibodies showed reactivity with the different combinations of p120 (CagA), p95 (VacA), p29 (UreA) and p66 (UreB) antigens. The number of positive samples for CagA-IgG, VacA-IgG, UreA-IgG, CagA-IgA and UreA-IgA were 19, 17, 21, 8 and 4, respectively, while there were no positive sample for VacA-IgA. The antigenic distribution did not show any difference between age and sex of the patients. In our study the sensitivities of WB-IgG and WB-IgA methods were estimated as 100% and 39%, respectively, which were in accordance with the studies in literature. As a result, WB-IgG method appears to be useful and reliable for the detection of antibody profiles to H. pylori antigens and virulence factors, rather than routine and screening purposes, however the diagnostic value of WB-IgA method is low. It was thought that the results of our preliminary study should be confirmed by other studies including larger patient populations and control groups, in our country.