HELICOBACTER-PYLORI HUMAN POLYMORPHONUCLEAR LEUKOCYTE INTERACTION IN THE PRESENCE OF AMMONIA

Objective: To determine if the ammonia produced by Helicobacter pylori affects the phagocytic ability of human polymorphonuclear leucocytes as measured by the oxidative burst. Methods: Interactions between opso nized urease-positive and -negative strains of H. pylori with polymorp honuclear leucocytes were studied in two series oi experiments. In the first series of experiments, concentrations from 0 to 50 mM of NH4Cl were added to polymorphonuclear leucocytes. In the second series of ex periments, bacteria were pre-incubated for 1 h with urea (0 to 50 mM) before addition of phagocytes. Luminol-dependent chemiluminescence was measured every 5 min over a 50-min period. The pH was verified in eac h treatment. Results: Inhibition of chemiluminescence, increasing with concentration, was noted in all treatments when NH4Cl was added. When urea was added to urease-positive strains, chemiluminescence was sign ificantly reduced when compared to the urease-negative strain and the zymosan control. This effect could not be attributed to a change in pH in the experiments using NH4Cl or urea at a concentration of 5 mM and 10 mM. Conclusion: Ammonia generated by H. pylori may contribute to t he decreased activity of polymorphonuclear leucocytes in vivo.