The neutrophil-activating protein (HP-NAP) of Helicobacter pylori is a potent stimulant of mast cells.

Infection by Helicobacter pylori causes an acute inflammatory response followed by a chronic infection of the human gastric mucosa. A neutrophil-activating protein (HP-NAP) has been identified in H.pylori, and its role in infection and immune response is currently under investigation. Here, we show that HP-NAP induces beta-hexosaminidase release and interleukin-6 production in peritoneal mast cells, two actions which are completely inhibited by pertussis toxin. We also show that in polarized epithelial cell monolayers HP-NAP translocates from the apical to the basolateral domain, where mast cells are located. These findings characterize HP-NAP as an inflammatory factor of H.pylori that is effective from the beginning of the inflammatory cascade.