Helicobacter pylori-human polymorphonuclear leucocyte interaction in the presence of ammonia

To determine if the ammonia produced by Helicobacter pylori affects the phagocytic ability of human polymorphonuclear leucocytes as measured by the oxidative burst.

Interactions between opsonized urease-positive and -negative strains of H. pylori with polymorphonuclear leucocytes were studied in two series of 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 experiments, 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 each treatment.

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 significantly 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.

Ammonia generated by H. pylori may contribute to the decreased activity of polymorphonuclear leucocytes in vivo.