In the present study we ascertained whether cagA positive and negative H. pylori strains release water soluble products that can influence the production of gastric mucosal cytokines and endocrine (gastrin) or exocrine (pepsinogen C) secretion in 23 H. pylori positive and 19 H. pylori negative patients. Antral biopsies were obtained to classify inflammation, activity, atrophy, intestinal metaplasia and H. pylori density grade. The cagA gene was identified by means of the polymerase chain reaction (PCR) in H. pylori positive colonies after culture of mucosal samples. Three antral biopsies from each patient were incubated with (1.) Water extracts from cagA positive, (2.) Water extracts from cagA negative strains or (3.) H2O (control) at 37 degrees C in a CO2 incubator for 24 hrs. Gastrin, pepsinogen C, IL-1 beta, IL-8, GMCSF, and TNF alpha were measured in the supernatants and mucosal homogenates. H. pylori infection was significantly associated with an increased antral inflammation and activity (chi 2 = 21.7, p < 0.001 and chi 2 = 42.0, p < 0.001), and increased mucosal levels of IL-1 beta, IL-8 and TNF alpha. Water extracts from cagA positive strains enhanced the release of PGC in mucosal biopsy supernatants (p < 0.05) when patients were considered overall and the release of TNF alpha (p < 0.05) when only patients with duodenal ulcer were considered. Water extracts from cagA negative strains stimulated gastrin secretion (p < 0.05). None of the remaining cytokines were influenced by H. pylori water extracts. In conclusion, pepsinogen C and TNF alpha can be induced by cagA positive water extracts and may contribute to damage the gastric and duodenal mucosa. Our findings indicate that in patients with H. pylori infection the increase of the mucosal levels of IL-1 beta and IL-8 does not depend on H. pylori water soluble products, but probably depends on the entire bacterium.