Differences in peripheral blood lymphocyte phenotypes between Helicobacter pylori-positive children and adults with duodenal ulcer.

The immunological mechanisms involved in the development of duodenal ulcer, especially in childhood, are unclear. Helicobacter pylori-positive children and adults, with and without duodenal ulcer, were therefore compared with respect to CD4(+) T-cells, and CD8(+) T-cells, B-cells and B1a-cells, as well as cell activation (CD4(+)/HLA-DR(+) and CD8(+)/HLA-DR(+)) and co-stimulatory (CD4(+)/CD28(+) and CD8(+)/CD28(+)) markers, in peripheral blood. Children with and without duodenal ulcer differed significantly. In particular, there was a phenotypic change in CD8(+) T-cells from children with ulcer that involved a 200% increase in the number of CD8(+)/HLA-DR(+) cells/mm(3) and a decrease of 34.2% in the number of CD8(+)/CD28(+) cells/mm(3). This phenotype of chronically activated memory CD8(+) T-cells, which has also been observed in patients with AIDS and tuberculosis, is associated with disease severity and progression. A lower frequency of B1a-cells was also observed in the group of children with ulcer. Conversely, no difference between infected adults with and without ulcer was observed, but the percentage of CD4(+)/HLA-DR(+) cells was lower in adults with ulcer, suggesting that a down-regulated immune response may play a role in the development of duodenal ulcer in adults. Gastric inflammation correlated positively with CD4(+) and chronically activated CD4(+) T-cells in children and adults without duodenal ulcer, respectively. These results suggest that there are differences in the immunophenotyping profile between H. pylori-positive children and adults with duodenal ulcer, indicating the possibility of distinct immune mechanisms in the development of the disease according to age.

The interrelationship between Helicobacter pylori vacuolating cytotoxin and gastric carcinoma.

OBJECTIVE: We aimed to determine whether cytotoxin-positive Helicobacter pylori strains are associated with gastric carcinoma. METHODS: We studied 130 patients: 57 H. pylori-positive patients with gastric carcinoma, 53 H. pylori-positive patients without gastric carcinoma, and 20 H. pylori-negative subjects. The ability of H. pylori strains to produce vacuolating cytotoxin was tested in INT-407 and HeLa cells. The presence of antibodies to cytotoxin was investigated in blood serum from all subjects by immunoblotting. Fragments of the gastric mucosa from patients without gastric carcinoma and H. pylori-negative subjects were obtained for histopathological study. RESULTS: Considering the results as a whole, 40 (70.2%) patients with and 22 (41.5%) without gastric carcinoma were colonized by cytotoxin-positive strains. Antibodies against cytotoxin were not observed in the serum from 17 (29.8%) gastric carcinoma patients and from 31 (58.5%) patients without gastric carcinoma. H. pylori strains isolated from these patients did not produce cytotoxin in vitro. In regard to cytotoxin positivity, a significant difference was observed between patients with and without gastric carcinoma (p=0.004; odds ratio [OR]: 3.3; 95% confidence interval [CI]: 1.4-7.9). Higher scores of mononuclear (p=0.0001) and polymorphonuclear (p=0.000003) cells were observed in the antral mucosa from H. pylori-positive patients without gastric carcinoma infected by cytotoxin-positive strains than in those harboring cytotoxin-negative strains. CONCLUSION: Cytotoxin-producing H. pylori strains were more frequently observed in patients with gastric carcinoma and this aspect emphasizes the role of cytotoxin in the genesis of the tumor.