Immunopathogenesis of human gastrointestinal infection by Anisakis simplex

Background: Anisakis simplex is a parasite of fish, and in the case of huma n infestation, it should be considered as a possible cause of gastrointesti nal disease, especially in countries where raw or undercooked fish is a fre quent food. Clinical features of anisakiasis may simulate acute abdominal p ain, such as that found in patients with gastric ulcers, appendicitis, and Crohn's disease. Furthermore, many cases of anisakiasis are diagnosed as eo sinophilic gastroenteritis, which is a broad term for a specific disease. Objective: The purpose of this study was to investigate the immunopathogene sis of human gastrointestinal infestation by A simplex. Methods: Thirteen intestinal biopsy specimens from patients with anisakiasi s were analyzed for the presence of messenger (m)RNA for different cytokine s and inflammatory mediators by RT-PCR. Specific IgE, eosinophil cationic p rotein, eosinophil protein X, and tryptase levels were measured in each pat ient's serum. Also, cell cultures were set up with lymphocytes from some pa tients and stimulated in vitro with Anisakis and Ascaris antigens. Results: We performed immunologic phenotyping in 13 patients. All patients underwent biopsy after emergency surgery caused by episodes of acute abdomi nal pain. In all cases inflammatory infiltrate composed of eosinophils and lymphocytes was found in the intestinal wall. We demonstrated that after in festation, a T-H2-type immune response occurred. Also, major basic protein, nitric oxide, and eotaxin were found in the tissue, and eosinophil cationi c protein and eosinophil protein X levels were elevated in sera. Conclusion: These data and in vitro lymphocyte cultures indicate that a T-H 2 mechanism plays an important role in the inflammatory infiltrate produced by the anchorage of parasites in the gastrointestinal wall.