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

Biol Psychiatry. 2005 Apr 1;57(7):813-6. doi: 10.1016/j.biopsych.2004.12.008.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / blood*
  • Alzheimer Disease / diagnostic imaging
  • Alzheimer Disease / immunology*
  • Amyloid beta-Peptides / blood
  • Amyloid beta-Peptides / immunology*
  • Autoantibodies / blood*
  • Case-Control Studies
  • Female
  • Humans
  • Immunoassay / methods
  • Immunoprecipitation / methods
  • Male
  • Middle Aged
  • Peptide Fragments / blood
  • Peptide Fragments / immunology*
  • Radioligand Assay / methods
  • Radionuclide Imaging


  • Amyloid beta-Peptides
  • Autoantibodies
  • Peptide Fragments
  • amyloid beta-protein (1-42)