HIGH PREVALENCE OF NEUTRALIZING ACTIVITY TO HELICOBACTER-PYLORI CYTOTOXIN IN SERUM OF GASTRIC-CARCINOMA PATIENTS

Helicobacter pylori infection is causally related to chronic type-B ga stritis, and may also be associated with an increased risk of gastric carcinoma. Vacuolating cytotoxin, which is an 87-kDa protein secreted by H. pylori, induced eukaryotic cell vacuolation in vitro. To determi ne whether there is an association between H. pylori vacuolating cytot oxin and gastric carcinoma, we investigated several characteristics of H. pylori infection, i.e., isolation of H. pylori from gastric biopsi es, antibodies specific for H. pylori, detection of neutralizing activ ity to vacuolating cytotoxin in serum and immunological detection of c ytotoxin by serum. Out of 6 sera from gastric-carcinoma patients, all showed the neutralizing activity to vacuolating cytotoxin, in contrast to 3 of 5 sera from peptic-ulcer patients. Normal individuals showed no neutralizing activity. All sera possessing the neutralizing activit y recognized an 87-kDa protein band by Western blot analysis. Our resu lts confirmed that cytotoxin-neutralizing activity in human sera was a ssociated with immuno-detection of an 87-kDa protein. Ro further evalu ate neutralizing activity in serum from gastric-carcinoma patients, we retrospectively analyzed frozen-stocked serum samples from 22 gastric -carcinoma patients. Sera from 21 of these 22 patients exhibited neutr alizing activity. These sera were also checked for antibodies to H. py lori, using an ELISA; 16 sera showed positive results. Our results ind icate that detection of cytotoxin-neutralizing activity in sera is str ongly associated with H. pylori infection, and probably with gastric c arcinoma, and is also of interest in the diagnosis of H. pylori infect ion.