title: Seroreactivity to 19.5-kDa antigen in combination with absence of seroreactivity to 35-kDa antigen is associated with an increased risk of gastric adenocarcinoma.
abstract: BACKGROUND
  Only a minority of those infected with Helicobacter pylori will develop gastric cancer. Stratification of H. pylori strains based on carcinogenic potential will provide a basis for selective surveillance and eradication therapy. We studied the anti-H. pylori antibody profile in Asian patients with gastric adenocarcinoma to identify any H. pylori antigen that may be associated with an increased or decreased risk of gastric carcinoma.
  
  
  METHODS
  A case-control study comparing the seroprevalence of antibodies with various H. pylori antigens in Singaporeans with gastric adenocarcinoma and the normal Singaporean population was carried out using both conventional immunoglobulin (Ig) G enzyme-linked immunosorbent assay (ELISA) and Western blot immunoassay.
  
  
  RESULTS
  The seroprevalence among 44 gastric adenocarcinoma cases (70.5% males, mean age 66.7 +/- 13.5 years) and 261 controls (49.8% males, mean age 61.5 +/- 4.1 years) was 90.9% vs. 50.2% by IgG ELISA. In the H. pylori-positive male population, those suffering from gastric adenocarcinoma had significantly lower seroreactivity to the 35-kDa antigen compared with asymptomatic controls (p =.0198, OR = 3.79, 95% CI 1.24-11.61). Seropositivity to the 19.5 kDa antigen was also found to be associated with the presence of gastric adenocarcinoma in Singaporean males (p =.022, OR = 4.17, 95% CI 1.22-14.28). A 'high-risk' phenotype consisting of absence of a band at 35-kDa in combination with the presence of a band at 19.5-kDa was significantly associated with the presence of gastric adenocarcinoma (p =.002, OR = 3.7, 95% CI 1.6-8.6).
  
  
  CONCLUSIONS
  Stratification of H. pylori strains based on their potential for carcinogenesis, such as those strains that are seropositive for the 19.5 kDa antigen and seronegative for the 35-kDa antigen, may provide a basis for selective eradication of H. pylori infection and future vaccine development.
authors.affiliation: Division of Gastroenterology, Department of Medicine, Changi General Hospital, Singapore.
authors.forename: Tju Siang
authors.initials: TS
authors.lastname: Chua
authors.forename: Kwong Ming
authors.initials: KM
authors.lastname: Fock
authors.forename: Yiong Huak
authors.initials: YH
authors.lastname: Chan
authors.forename: Subbiah
authors.initials: S
authors.lastname: Dhamodaran
authors.forename: Chee Seng
authors.initials: CS
authors.lastname: Sim
authors.forename: Tay Meng
authors.initials: TM
authors.lastname: Ng
authors.forename: Eng Kiong
authors.initials: EK
authors.lastname: Teo
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology / Q000382:microbiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D015153:Blotting, Western; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016481:Helicobacter Infections / Q000276:immunology / Q000382:microbiology; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012846:Singapore / Q000453:epidemiology; D013274:Stomach Neoplasms / Q000276:immunology / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial