Serological Responses of FldA and Small‐Molecular‐Weight Proteins of Helicobacter pylori : Correlation with the Presence of the Gastric MALT Tissue

Purpose.  We tested whether the serological response to Flavodoxin‐A (FldA) protein and anti‐ Helicobacter pylori immunoblots correlated to the degree of mucosa‐associated lymphoid tissue (MALT) in the stomach. Methods.  Eighty H. pylori ‐infected patients with different degrees of MALT in the stomach were investigated with serum sampling and endoscopy on enrolment, the 2nd and the 12th months after anti‐ H. pylori therapy. All sera were tested for the anti‐FldA protein and anti‐ H. pylori immunoblots, including 19.5, 26.5, 30, 35, 89, and 116 KDa (CagA). Regression of follicular gastritis was assessed by histology. Results.  Patients with dense lymphoid follicles had higher prevalence rates of anti‐FldA protein, 19.5, 26.5, and 30 KDa antibodies of H. pylori ( p <  .05). Histologic downgrade of MALT was observed in 25% (10/40) of patients in the 2nd month and in 60% (23/38) in the 12th month after H. pylori therapy. After H. pylori eradication, the patients with MALT and dense lymphoid follicles had significantly negative seroconversions of 19.5, 26.5, 30, and 35 KDa antibodies ( p  < .05), but not of CagA and FldA. Conclusion.  Patients with gastric MALT and dense lymphoid follicles had different anti‐ H. pylori serological responses to those with scanty or an absence of lymphoid follicles. The negative seroconversion of the smaller‐molecular‐weight proteins, but not CagA and FldA, may correlate with the regression of MALT by H. pylori eradication.