Low seroprevalence of Helicobacter pylori antibodies in historical sera of patients with Crohn's disease.

BACKGROUND: Our aim was to determine the seroprevalence of Helicobacter pylori antibodies in historical sera from a large group of patients with Crohn's disease and to compare the findings with those of a control group of healthy blood transfusion donors.
METHODS: The historical sera from 386 patients with Crohn's disease were studied (serum age, 9.9 years; range, 0.4-21.6 years). Serum IgG and IgA H. pylori antibodies were measured with enzyme-linked immunosorbent assay. Western blots (detecting IgG only) were also used to study a subpopulation of the patients' sera and to assess the presence of cagA bands, indicating a cytotoxic variety of H. pylori. The serology of the Crohn's disease patients was compared with that of 277 age-matched controls. A longitudinal follow-up study of 14 IgG and IgA anti-H. pylori-positive and 14 IgG- and IgA-negative Crohn's disease patients was also performed (mean follow-up, 7.6 years; range, 1.7-20.5 years).
RESULTS: Of the total Crohn's disease patients, 47 (12.2%) had IgG antibodies against H. pylori, 67 (17.4%) had IgA antibodies, and 31 (8.0%) had both IgG and IgA antibodies. The corresponding antibody positivities for the controls were 98 (35.4%) for IgG, 77 (27.8%) for IgA, and 64 (23.1%) for both IgG and IgA. When compared, with the control group, the seroprevalence of H. pylori in the Crohn's disease patients was significantly lower (P < or = 0.002). In addition the relative IgG response of the patients was lower than the IgA response. The opposite was true for the controls. There was no difference in the absolute levels of H. pylori antibodies between patients and controls. In the follow-up study two patients initially IgG-positive for H. pylori became negative over time; these patients had been treated for their infection. the rest, who continued to be positive, were not treated. One patient who was initially IgA-positive also became IgA-negative over time. The follow-up group, who were initially IgG- and IgA-negative, remained IgG-negative with time, and two patients became IgA-positive. Findings of anti-H. pylori IgG were confirmed with Western blots. Furthermore, these showed that of the H. pylori-positive patients (indicated by their IgG positivity), 66% were infected with a cytotoxic (cagA-positive) variety, compared to 69.4% of the controls.
CONCLUSIONS: Patients with Crohn's disease have a lower prevalence of H. pylori antibodies than an age-matched control group. There is a reversal of the relative IgG and IgA responses in Crohn's disease patients compared with the controls. Of the Crohn's disease patients with H. pylori most are infected with cytotoxic varieties, similar to controls.