HUMORAL IMMUNE-RESPONSE AGAINST HELICOBACTER-PYLORI AS DETERMINED BY IMMUNOBLOT

An immunoblot method has been evaluated to diagnose Helicobacter pylor i infection serologically by comparing 69 serum specimens from patient s with a positive Gram stain and/or culture result and a positive urea se test on biopsy material, as well as 51 serum specimens from patient s with at least 4 negative urease tests, and negative microscopy and c ulture results. Sensitivity and specificity was found to be 100%. Reco gnition of the cross-reacting flagellin (66 kDa), flagellar sheath pro tein (51 kDa), and a 14 kDa protein are not a criterion for a current H. pylori infection. On the other hand, any combination of at least tw o of the 180, 120, 90, 75, 67, 29.5 and 19 kDa bands were diagnostic o f infection. Three H. pylori strains, which were compared with both ge l electrophoretic analyses and immunoblot reactivity, exhibited in par t strong qualitative and quantitative differences that particularly af fect the 120 kDa pathogenic factor, the large urease subunit and other proteins especially in the molecular mass range from 50 to 67 kDa. Ig G immunoblot patterns showed that the choice of H. pylori strain, as w ell as a reproducible and standardizable antigen preparation, is of gr eat importance for the reliability of serodiagnostic tests. The immuno blot method was found to be a valuable tool for the semiquantitative c onfirmation of results achieved with other serological methods as well as optimization and quality control of the antigens used for serodiag nostic purposes.