title: Detection of anti-Helicobacter pylori antibodies in serum and duodenal fluid in peptic gastroduodenal disease.
abstract: OBJECTIVE
  To study the diagnosis of Helicobacter pylori (H pylori) infection through the determination of serum levels of anti-H pylori IgG and IgA antibodies, and the levels of anti-H pylori IgA antibodies in duodenal fluid.
  
  
  METHODS
  Data were collected from 93 patients submitted to upper digestive endoscopy due to dyspeptic symptoms. The patients were either negative (group A) or positive (group B) to H pylori by means of both histological detection and urease tests. Before endoscopy, peripheral blood was collected for the investigation of anti-H pylori IgG and IgA antibodies. To perform the urease test, biopsies were obtained from the gastric antrum. For the histological evaluation, biopsies were collected from the gastric antrum (greater and lesser curvatures) and the gastric body. Following this, duodenal fluid was collected from the first and second portions of the duodenum. For the serological assaying of anti-H pylori IgG and IgA, and anti-H pylori IgA in duodenal fluids, the ELISA method was utilized.
  
  
  RESULTS
  The concentration of serum IgG showed sensitivity of 64.0%, specificity of 83.7%, positive predictive value of 82.0%, negative predictive value of 66.6% and accuracy of 73.1% for the diagnosis of H pylori infection. For the same purpose, serum IgA showed sensitivity of 72.0%, specificity of 65.9%, positive predictive value of 72.0%, negative predictive value of 67.4% and accuracy of 69.8%. If the serological tests were considered together, i.e. when both were positive or negative, the accuracy was 80.0%, sensitivity was 86.6%, specificity was 74.2%, positive predictive value was 74.2% and negative predictive value was 86.6%. When values obtained in the test for detecting IgA in the duodenal fluid were analyzed, no significant difference (P = 0.43) was observed between the values obtained from patients with or without H pylori infection.
  
  
  CONCLUSIONS
  The results of serum IgG and IgA tests for H pylori detection when used simultaneously, are more efficient in accuracy, sensitivity and negative predictive value, than those when used alone. The concentration of IgA antibodies in duodenal fluid is not useful in identifying patients with or without H pylori.
authors.affiliation: Department of Surgery, ABC Faculty of Medicine, Avenida Principe de Gales 821, Santo Andre, São Paulo, 09060-650, Brazil.
authors.forename: Angelo
authors.initials: A
authors.lastname: Locatelli
authors.forename: Wilson Roberto
authors.initials: WR
authors.lastname: Catapani
authors.forename: Claudio Rufino
authors.initials: CR
authors.lastname: Gomes
authors.forename: Claudilene Battistin Paula
authors.initials: CB
authors.lastname: Silva
authors.forename: Jaques
authors.initials: J
authors.lastname: Waisberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000032:analysis / Q000097:blood*; D004386:Duodenum / Q000382:microbiology*; D016099:Endoscopy, Gastrointestinal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D010437:Peptic Ulcer / Q000382:microbiology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests
chemical_list: D000907:Antibodies, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G