title: Increased Avidity of the Sambucus nigra Lectin-Reactive Antibodies to the Thomsen-Friedenreich Antigen as a Potential Biomarker for Gastric Cancer.
abstract: OBJECTIVE
  To determine whether the naturally occurring Thomsen-Friedenreich (TF) antigen-specific antibodies differ in avidity between cancer patients and controls to find a novel biomarker for stomach cancer.
  
  
  METHODS
  Serum samples were taken from patients with cancer and controls. The level of TF-specific antibodies and their sialylation were determined using ELISA with synthetic TF-polyacrylamide conjugate as antigen and sialic acid-specific Sambucus nigra agglutinin (SNA). The avidity was determined using ammonium thiocyanate as a chaotrope.
  
  
  RESULTS
  A significantly higher SNA lectin binding to anti-TF antibodies was found in cancer patients irrespective of disease stage. The avidity of only IgM TF-specific antibodies was significantly higher in cancer patients compared to controls. The SNA-positive anti-TF antibodies of cancer patients showed a significantly higher avidity, P < 0.001. The sensitivity and specificity of this increase for gastric cancer were 73.53% and 73.08%, respectively, with a 73.2% diagnostic accuracy. The higher avidity of SNA-reactive anti-TF antibodies was associated with a benefit in survival of stage 3 cancer patients.
  
  
  CONCLUSIONS
  The SNA-reactive TF-specific antibodies display a significantly higher avidity in gastric cancer patients compared to controls, which can be used as a potential serologic biomarker for gastric cancer. It appears that IgM is the main target responsible for the above changes.
authors.affiliation: Department of Oncology and Immunology, National Institute for Health Development, Hiiu 42, 11619 Tallinn, Estonia.
authors.forename: Oleg
authors.initials: O
authors.lastname: Kurtenkov
authors.affiliation: Department of Oncology and Immunology, National Institute for Health Development, Hiiu 42, 11619 Tallinn, Estonia.
authors.forename: Kersti
authors.initials: K
authors.lastname: Klaamas
mesh_terms: D000328:Adult; D000368:Aged; D000915:Antibody Affinity; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000276:immunology*; D014408:Biomarkers, Tumor / Q000097:blood* / Q000276:immunology; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D037121:Plant Lectins / Q000276:immunology*; D054788:Ribosome Inactivating Proteins / Q000276:immunology*; D013274:Stomach Neoplasms / Q000097:blood* / Q000473:pathology
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D007075:Immunoglobulin M; D037121:Plant Lectins; C050600:Sambucus nigra lectins; C016467:Thomsen-Friedenreich antigen; D054788:Ribosome Inactivating Proteins