Correlations between the CagA Antigen and Serum Levels of Anti-Helicobacter pylori IgG and IgA in Children

We tested correlations between anti-Helicobacter pylori IgG and IgA levels and the urease test, anti-CagA protein antibody, degree of gastritis, and age. In total, 509 children (0–15 years) were enrolled. Subjects were stratified as 0–4 years (n = 132), 5–9 years (n = 274), and 10–15 years (n = 103) and subjected to the urease test, histopathology, ELISA, and western blot using whole-cell lysates of H. pylori strain 51. The positivity rate in the urease test (P = 0.003), the degree of chronic gastritis (P = 0.021), and H. pylori infiltration (P < 0.001) increased with age. The median titer for anti-H. pylori IgG was 732.5 IU/mL at 0–4 years, 689.0 IU/mL at 5–9 years, and 966.0 IU/mL at 10–15 years (P < 0.001); the median titer for anti-H. pylori IgA was 61.0 IU/mL at 0–4 years, 63.5 IU/mL at 5–9 years, and 75.0 IU/mL at 10–15 years (P < 0.001). The CagA-positivity rate was 26.5% at 0–4 years, 36.5% at 5–9 years, and 46.6% at 10–15 years for IgG (P = 0.036), and 11.3% at 0–4 years, 18.6% at 5–9 years, and 23.3% at 10–15 years for IgA (P < 0.001). Anti-H. pylori IgG and IgA titers increased with the urease test grade, chronic gastritis degree, active gastritis, and H. pylori infiltration. Presence of CagA-positivity is well correlated with a high urease test grade and high anti-H. pylori IgG/IgA levels.