The pathogenic role of human neutrophils has been implicated in Helicobacter pylori-associated gastritis. Ecabet sodium, a locally acting antiulcer drug, has anti-H. pylori actions. The aim of this study was to examine the effects of ecabet on the ability of H. pylori to stimulate human neutrophils. H. pylori were added to 1 x 10(5) neutrophils and incubated for 30 min in the presence of ecabet. Bacterial suspensions which had been incubated with ecabet for 30 min were also used to stimulate neutrophils. The intracellular production of reactive oxygen species was measured with a FACScan. Bacterial suspensions were also added to neutrophils in the presence of ecabet and incubated at 37 degrees C for 12 h to measure interleukin (IL)-8 production by enzyme-linked immunosorbent assay. The mean fluorescence intensity was found to be attenuated dose-dependently by ecabet (P < 0.01). Ecabet also inhibited IL-8 production by neutrophils in a dose-dependent manner (P < 0.001). Bacteria with prior incubation with ecabet induced significantly lower IL-8 production than those without this incubation (P < 0.05). Ecabet sodium has preventive effects on the ability of H. pylori to stimulate human neutrophils. It may lead to reduced gastritis activity and decreased oxidative damage of the gastric mucosa in H. pylori-associated gastritis.