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.
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.
Brettschneider
Sylvia
S
Department of Psychiatry, Ludwig-Maximilian University Munich, Munich, Germany.
Morgenthaler
Nils G
NG
Teipel
Stefan J
SJ
Fischer-Schulz
Christina
C
Bürger
Katharina
K
Dodel
Richard
R
Du
Yansheng
Y
Möller
Hans-Jürgen
HJ
Bergmann
Andreas
A
Hampel
Harald
H
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
D016229:Amyloid beta-Peptides; D001323:Autoantibodies; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)