title: Decreased serum amyloid beta(1-42) autoantibody levels in Alzheimer's disease, determined by a newly developed immuno-precipitation assay with radiolabeled amyloid beta(1-42) peptide.
abstract: BACKGROUND
  Autoantibodies against amyloid beta (A beta) peptide found in patients with Alzheimer's disease (AD) also occur naturally in the general population independently of the cognitive status.
  
  
  METHODS
  We compared serum A beta(1-42) autoantibody levels (A beta(1-42)-AL) of 96 AD patients and 30 healthy elderly control subjects (HC), assessing their diagnostic value for AD with a newly developed immunoprecipitation assay with radiolabeled A beta(1-42) peptide.
  
  
  RESULTS
  We found a highly significant decrease of A beta(1-42)-AL in AD patients (p = .001) independently of age, cognitive status, and apolipoprotein E epsilon4 carrier status. Amyloid beta(1-42) autoantibody levels were correlated with gender in AD, with a higher level occurring in women. When A beta(1-42) autoantibody sensitivity (specificity) was set >80%, specificity (sensitivity) was below 50% to correctly allocate patients and healthy control subjects.
  
  
  CONCLUSIONS
  Our data indicate a potentially pathophysiologic decrease of serum A beta(1-42) antibodies in AD. Amyloid beta(1-42) antibodies in the serum alone, however, seem not to be useful as a diagnostic marker of AD.
authors.affiliation: Department of Psychiatry, Ludwig-Maximilian University Munich, Munich, Germany.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Brettschneider
authors.forename: Nils G
authors.initials: NG
authors.lastname: Morgenthaler
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Teipel
authors.forename: Christina
authors.initials: C
authors.lastname: Fischer-Schulz
authors.forename: Katharina
authors.initials: K
authors.lastname: Bürger
authors.forename: Richard
authors.initials: R
authors.lastname: Dodel
authors.forename: Yansheng
authors.initials: Y
authors.lastname: Du
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Möller
authors.forename: Andreas
authors.initials: A
authors.lastname: Bergmann
authors.forename: Harald
authors.initials: H
authors.lastname: Hampel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000000981:diagnostic imaging / Q000276:immunology*; D016229:Amyloid beta-Peptides / Q000097:blood / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood / Q000276:immunology*; D011869:Radioligand Assay / Q000379:methods; D011877:Radionuclide Imaging
chemical_list: D016229:Amyloid beta-Peptides; D001323:Autoantibodies; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)