ANTIBODY-SECRETING CELLS IN THE STOMACHS OF SYMPTOMATIC AND ASYMPTOMATIC HELICOBACTER PYLORI-INFECTED SUBJECTS

In this study we analyzed whether infection with Helicobacter pylori g ives rise to specific B-cell responses against a number of putative vi rulence factors of H. pylori, e.g., urease, flagellin, and different b acterial surface antigens, locally in the gastric mucosa, This was stu died in antrum and corpus biopsies collected from 11 H. pylori-infecte d patients with duodenal ulcers, 11 asymptomatic H. pylori carriers, a nd 13 noninfected, healthy controls. Mononuclear cells were isolated f rom the biopsies and assayed for frequencies of total and H. pylori-sp ecific antibody-secreting cells (ASCs) by means of the enzyme-linked i mmunospot technique. The H. pylori-infected subjects had remarkably hi gher frequencies of total immunoglobulin A (IgA)- and IgM-secreting ce lls than the noninfected subjects, while the frequencies of IgG-secret ing cells were virtually the same in the different groups. In addition , most of the infected subjects had IgA ASCs reacting with H. pylori m embrane proteins, flagellin, and urease, while none of the noninfected subjects had any detectable H. pylori-reactive ASCs, Furthermore, hal f of the infected subjects also had ASCs reacting with a Helicobacter- specific 26-kDa protein, while only a few of them had ASCs reacting wi th neutrophil-activating protein, the neuraminyllactose-binding hemagg lutinin HpaA, or lipopolysaccharides purified from different H. pylori strains. The frequencies of H. pylori-specific ASCs in the antrum and corpus were almost identical, and no differences in either antigen sp ecificity or magnitude of the B-cell response in the stomach could be detected between the ulcer patients and the asymptomatic H. pylori car riers. This study demonstrates that H. pylori infection induces strong antibody responses in the human gastric mucosa, both in asymptomatic carriers and in duodenal ulcer patients. However, the outcome of infec tion could not be explained by differences in the local B-cell respons e to any of the antigens used in this study.