Antigen-bound and free β-amyloid autoantibodies in serum of healthy adults

PLoS One. 2012;7(9):e44516. doi: 10.1371/journal.pone.0044516. Epub 2012 Sep 4.

Abstract

Physiological β-amyloid autoantibodies (Aβ-autoantibodies) are currently investigated as potential diagnostic and therapeutic tools for Alzheimer's disease (AD). In previous studies, their determination in serum and cerebrospinal fluid (CSF) using indirect ELISA has provided controversial results, which may be due to the presence of preformed Aβ antigen-antibody immune complexes. Based on the epitope specificity of the Aβ-autoantibodies, recently elucidated in our laboratory, we developed (a) a sandwich ELISA for the determination of circulating Aβ-IgG immune complexes and (b) an indirect ELISA for the determination of free Aβ-autoantibodies. This methodology was applied to the analysis of serum samples from healthy individuals within the age range of 18 to 89 years. Neuropsychological examination of the participants in this study indicated non-pathological, age-related cognitive decline, revealed especially by tests of visual memory and executive function, as well as speed-related tasks. The ELISA serum determinations showed significantly higher levels of Aβ-IgG immune complexes compared to free Aβ-autoantibodies, while no correlation with age or cognitive performance of the participants was found.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / blood
  • Alzheimer Disease / diagnosis*
  • Amino Acid Sequence
  • Amyloid beta-Peptides / immunology*
  • Antigen-Antibody Complex* / blood
  • Autoantibodies* / blood
  • Cognitive Dysfunction / blood
  • Cognitive Dysfunction / diagnosis*
  • Enzyme-Linked Immunosorbent Assay / methods
  • Epitopes / genetics
  • Female
  • Germany
  • Humans
  • Immunoglobulin G / immunology
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Neuropsychological Tests

Substances

  • Amyloid beta-Peptides
  • Antigen-Antibody Complex
  • Autoantibodies
  • Epitopes
  • Immunoglobulin G

Grants and funding

This research was funded as an interdisciplinary project within the WIN-Kolleg (Junior Academy for Young Scholars and Scientists) of the Heidelberg Academy of Sciences, Heidelberg, Germany, awarded to IK, M. Manea and CvA, by the Zukunftskolleg (IK and M. Manea) and Research Center Proteostasis (MP), University of Konstanz. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.