The humoral immuneresponse to Helicobacter pylori infection in children with gastrointestinal symptoms.

The prevalence of Helicobacter pylori is high in Eastern Europe. The purpose of this study was to estimate the prevalence of H. pylori in symptomatic Lithuanian children and to identify the infection by clinicopathological and serological analyses. One hundred sixteen symptomatic children (age 8-16) with gastritis and duodenal ulcer were included. Biopsies were histologically assessed according to the Sydney-System. Serum IgG antibodies against H. pylori were detected by an enzyme-linked immunosorbent assay (ELISA), using low molecular mass antigen. The western blot technique was used to detect serum antibodies against the cytotoxin-associated protein (CagA) using whole cell antigen. Histologically the prevalence of H. pylori infection was 79% and not influenced by demographic factors. Mucosal inflammation and atrophy were associated with a H. pylori infection. Intestinal metaplasia was found in eight children, suggesting early H. pylori acquisition in life. Increased levels of IgG antibodies were detected in 57% of children. The prevalence of IgG antibodies was significantly higher in patients with duodenal ulcer compared to children with gastritis. Forty-four (67%) H. pylori-seropositive children had antibodies against CagA. Low molecular weight-ELISA and whole cell-western blot results were significantly associated with histopathology, the presence of duodenal ulcer and the CagA status. A high number of false seronegative cases were due to poor immunological responses in children and poor locally validated tests. The prevalence of H. pylori infection in Lithuanian children is higher compared to Western Europe. The infection is acquired in early life. Diagnosing H. pylori infection, serology is helpful, but endoscopy/histology remains as gold standard.