Background and Aims: Several studies have indicated that host factors are important in Helicobacter pylori-induced gastroduodenal diseases. We examined the pathological role of host immune responses in H. pylori infection by reconstituting components of the human immune system into severe combined immunodeficient (SCID) mice by transplantation of peripheral blood mononuclear cells (PBMCs) from H. pylori-infected patients. Methods: PBMCs obtained from patients with mucosa-associated lymphoid tissue (MALT) lymphoma were injected intraperitoneally into SCID mice, designated MALToma-hu-SCID mice. One month after transplantation, H. pylori was administered orally to the mice. The mice were killed and examined for pathological changes and immunologic features. Results: Human lymphocytes were detected in hu-SClD mice, and T- and B-cell functions were preserved for 1 month. Administration of H. pylori led to gastric ulcers with bleeding in the MALToma-hu-SCID mice. The gastric mucosa of control mice injected with Escherichia coli or transplanted with PBMCs from patients with peptic ulcers or gastritis or from healthy volunteers showed no pathological changes. Conclusions: Host immune responses against H. pylori appear to be involved in the development of gastric ulcers in patients who have MALT lymphoma.
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