CHARACTERIZATION OF A HELICOBACTER-PYLORI NEUTROPHIL-ACTIVATING PROTEIN

Helicobacter pylori-associated gastritis is mainly an inflammatory cel l response. In earlier work we showed that activation of human neutrop hils by a cell-free water extract of H. pylori is characterized by inc reased expression of neutrophil CD11b/CD18 and increased adhesiveness to endothelial cells. The work reported here indicates that the neutro phil-activating factor is a 150,000-molecular-weight protein (150K pro tein). Neutrophil proadhesive activity copurified with this protein, w hich is a polymer of identical 15K subunits. Specific antibody, prepar ed against the purified 15K subunit, neutralized the proadhesive activ ity of the pure protein and of water extracts obtained from different strains of H. pylori. The gene (napA) for this protein (termed HP-NAP, for H. pylori neutrophil-activating protein) was detected, by PCR amp lification, in all of the H. pylori isolates tested; however, there wa s considerable strain variation in the level of expression of HP-NAP a ctivity in vitro. HP-NAP could play an important role in the gastric i nflammatory response to H. pylori infection.