HIGHLY SIGNIFICANT ROLE OF HELICOBACTER-PYLORI UREASE IN PHAGOCYTOSISAND PRODUCTION OF OXYGEN METABOLITES BY HUMAN GRANULOCYTES

The contribution of Helicobacter pylori urease, the vacuolating cytoto xin VacA, and the 128-kDa protein CagA to the stimulation of human gra nulocytes in terms of phagocytosis and oxidative burst was evaluated. Blood was incubated with H. pylori strains and corresponding isogenic mutants lacking either the large urease subunit (UreB) or an accessory urease protein (UreG) or VacA or CagA. Phagocytosis and oxidative bur st were monitored by how cytometry. The UreB-lacking mutant was phagoc ytosed more efficiently (P < .001) and induced significantly less oxid ative burst (P < .001) than its parental strain or the UreG-lacking mu tant, which produces an enzymatically inactive urease. Values of the o ther mutants did not differ greatly from those of their parental strai n. These data indicate inflammatory effects of H. pylori urease causin g inhibition of phagocytosis and stimulation of oxidative burst by a p athway being largely independent of ammonia production.