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Differences in peripheral blood lymphocyte phenotypes between Helicobacter pylori-positive children and adults with
T Figueiredo Soares1, G Aguiar Rocha, A M Camargos Rocha
1Laboratory of Research in Bacteriology, Faculdade de Medicina/UFMG, Belo Horizonte, Brazil.
Insights
Pediatric duodenal ulcers show increased CD8(+) T-cells, suggesting chronic immune activation. Adult duodenal ulcers may involve a down-regulated immune response, indicating age-related differences in H. pylori immunopathogenesis.
Area of Science:
- Immunology
- Gastroenterology
- Pediatrics
Background:
- The immunological mechanisms underlying duodenal ulcer development, particularly in children, remain poorly understood.
- Helicobacter pylori infection is a major cause of duodenal ulcers, but age-dependent immune responses are not well characterized.
Purpose of the Study:
- To compare immunological profiles, including T-cell subsets and activation markers, in H. pylori-positive children and adults with and without duodenal ulcers.
- To investigate age-specific immune mechanisms contributing to duodenal ulcer pathogenesis.
Main Methods:
- Peripheral blood samples were analyzed for CD4(+) T-cells, CD8(+) T-cells, B-cells, and B1a-cells.
- Cell activation (HLA-DR) and co-stimulatory (CD28) markers on T-cells were quantified using flow cytometry.
- Immunophenotyping was compared between pediatric and adult groups with and without duodenal ulcers.
Main Results:
- Children with duodenal ulcers exhibited a significant increase in CD8(+) T-cells expressing HLA-DR (indicating chronic activation) and a decrease in CD8(+) T-cells expressing CD28.
- A lower frequency of B1a-cells was observed in children with duodenal ulcers.
- Adults with duodenal ulcers showed a lower percentage of CD4(+) T-cells expressing HLA-DR, suggesting a down-regulated immune response, contrasting with findings in children.
Conclusions:
- Distinct immunophenotypic profiles exist between H. pylori-positive children and adults with duodenal ulcers.
- Age-specific immune responses, including chronic T-cell activation in children and potential immune suppression in adults, may play different roles in duodenal ulcer development.
Abstract:
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.
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