LOCAL AND SYSTEMIC IMMUNE-RESPONSES IN HUMANS AGAINST HELICOBACTER-PYLORI ANTIGENS FROM HOMOLOGOUS AND HETEROLOGOUS STRAINS

The capacity of Helicobacter pylori to induce strain specific immune r esponses was studied in adult Swedish volunteers. Sera and gastric asp irates from 11 H. pylori-infected subjects were tested for specific an tibody levels against, respectively, lipopolysaccharides (LPS) and tot al membrane preparations (MPs) prepared from the study subjects' own s trains, as well as with corresponding antigens from two reference H. p ylori strains or heterologous strains collected from other subjects wi thin the study. It was found that sera from five of the 11 subjects ha d significantly higher IgA antibody titres against LPS from the homolo gous strain than against LPS from either of the reference strains and in five cases sera reacted with higher IgG titres against the homologo us LPS than with LPS preparations from the reference or heterologous p atient strains. Analyses of specific titres against MPs revealed that six sera had higher IgA titres and four sera had higher IgG titres aga inst MPs prepared from the subjects' own strains than against MPs from either of the two reference strains. Determination of specific antibo dies in gastric aspirates revealed significantly higher IgA titres aga inst LPS from the homologous H. pylori isolate than against CPS from t he two reference strains in five cases, and six aspirates reacted in h igher IgA titre with the homologous H. pylori MPs. Results from immuno blotting analyses of sera support induction of strain specific immune responses against H. pylori LPS. By means of specific monoclonal antib odies against H. pylori LPS, antigenic heterogeneity between the diffe rent CPS preparations tested was confirmed. (C) 1997 Academic Press Li mited.