Serum and urine Helicobacter pylori antibody titer after intravenous γ-globulin treatment for Kawasaki disease and its clearance

Background: It is not clear the effect of gamma-globulin therapy on results of enzyme-linked immunosorbent assays (ELISA) based on serum and urine for detection of Helicobacter pylori (H. pylori) antibodies, although the therapy can cause false-positive results in those assays. Methods: To examine the effect of intravenous gamma-globulin (IVIG) treatment on the results of ELISA based on serum and urine, levels of H. pylori IgG were measured in the serum and urine before and after IVIG therapy in IS children with Kawasaki disease (KD) uninfected with H. pylori. Results: The serum and urine H. pylori IgG levels decreased time-dependently after the IVIG therapy and there were significant differences (P < 0.01) in the levels prior to therapy and at 7 days and I month after the therapy. The significant difference in the H. pylori IgG levels prior to therapy and 3 months after the therapy was observed in the serum but not in the urine. Conclusion: The results suggest that gamma-globulin administration can cause false-positive results in ELISA based both on serum and urine for detection of H. pylori antibodies, and that the H. pylori antibodies cleared much more quickly from the urine than from the serum.