title: Phenotype of Gc-globulin influences the macrophage activating factor (MAF) levels in serum.
abstract: BACKGROUND
  Gc-globulin is a polymorphic protein with three phenotypes: Gc 1-1, Gc 2-1 and Gc 2-2. Deglycosylation of Gc-globulin results in a Gc-macrophage activating factor (Gc-MAF). This study investigated the potential of MAF as a tumour marker and the influence of Gc-phenotypes on serum MAF-concentrations.
  
  
  METHODS
  Gc-phenotype of 98 healthy individuals and 60 cancer patients was determined. MAF-levels of healthy individuals and cancer patients were analysed according to their Gc-phenotype using a Helix pomatia agglutinin-based ELISA. ROC curves analysed the efficiency of MAF as a tumour marker.
  
  
  RESULTS
  MAF-levels between controls and patients were significantly different (p<0.001). No phenotypic differences were found in the patients. In comparison with the controls, MAF-values were significantly lower in cancer patients carrying Gc 1-1 (p<0.01) and Gc 2-1 (p<0.001). No difference was observed in Gc 2-2 phenotype. Diagnostic accuracy of MAF as a tumour marker also demonstrated pronounced differences between Gc-phenotypes.
  
  
  CONCLUSIONS
  Gc-phenotype is a confounding factor when interpreting MAF-data. The value of MAF as a tumour marker varies according to phenotype. Future studies on MAF will have to consider the effect of Gc-phenotype.
authors.affiliation: Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Evi
authors.initials: E
authors.lastname: Debruyne
authors.forename: Marijn
authors.initials: M
authors.lastname: Speeckaert
authors.forename: Yannick Vande
authors.initials: YV
authors.lastname: Weygaerde
authors.forename: Joris
authors.initials: J
authors.lastname: Delanghe
mesh_terms: D000328:Adult; D000368:Aged; D001530:Belgium; D014408:Biomarkers, Tumor / Q000097:blood*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016130:Immunophenotyping / Q000379:methods*; D037102:Lectins / Q000032:analysis / Q000276:immunology; D008262:Macrophage Activation; D016215:Macrophage-Activating Factors / Q000097:blood*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood / Q000276:immunology* / Q000473:pathology; D011110:Polymorphism, Genetic / Q000276:immunology*; D012372:ROC Curve; D014809:Vitamin D-Binding Protein / Q000097:blood / Q000235:genetics* / Q000276:immunology
chemical_list: D014408:Biomarkers, Tumor; C038095:Helix lectin; D037102:Lectins; D016215:Macrophage-Activating Factors; D014809:Vitamin D-Binding Protein