title: False positive reactions for IgA and IgG anti-tissue transglutaminase antibodies in liver cirrhosis are common and method-dependent.
abstract: BACKGROUND
  Conflicting results were obtained in the assay of anti-transglutaminase (anti-tTG) autoantibodies in patients with chronic liver disease. In order to establish whether this was attributable to methodological differences, anti-tTG antibodies were assayed in a large number of patients suffering from liver cirrhosis (LC).
  
  
  METHODS
  54 patients with LC and 29 patients suffering from celiac disease (CD), used as controls, were tested for IgA and IgG anti-tTG with 11 different commercial methods.
  
  
  RESULTS
  In the patients with LC, positivity ranged from 0% to 33.3% for IgA anti-tTG and from 0% to 11.1% for anti-tTG of the IgG class. The largest number of false positives was found with methods that used tTG in association with gliadin peptides as antigen substrate. A significant association was found between IgA anti-tTG antibodies and serum immunoglobulin concentration.
  
  
  CONCLUSIONS
  The results of the various methods of assaying anti-tTG antibodies in patients with LC are highly variable, and the positives found are generally false positives, partly due to the high immunoglobulin concentration.
authors.affiliation: Immunologia Clinica e Virologia, Azienda Ospedaliera, S. Maria degli Angeli, Via Montereale 24, 33170 Pordenone, Italy. danilo.villalta@aopn.fvg.it
authors.forename: Danilo
authors.initials: D
authors.lastname: Villalta
authors.forename: Marina
authors.initials: M
authors.lastname: Crovatto
authors.forename: Sergio
authors.initials: S
authors.lastname: Stella
authors.forename: Elio
authors.initials: E
authors.lastname: Tonutti
authors.forename: Renato
authors.initials: R
authors.lastname: Tozzoli
authors.forename: Nicola
authors.initials: N
authors.lastname: Bizzaro
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D002446:Celiac Disease / Q000276:immunology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D008103:Liver Cirrhosis / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011503:Transglutaminases / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D011503:Transglutaminases