title: Antigen-bound and free β-amyloid autoantibodies in serum of healthy adults.
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.
authors.affiliation: Laboratory of Analytical Chemistry and Biopolymer Structure Analysis, Department of Chemistry, University of Konstanz, Konstanz, Germany.
authors.forename: Madalina
authors.initials: M
authors.lastname: Maftei
authors.forename: Franka
authors.initials: F
authors.lastname: Thurm
authors.forename: Vera Maria
authors.initials: VM
authors.lastname: Leirer
authors.forename: Christine A F
authors.initials: CA
authors.lastname: von Arnim
authors.forename: Thomas
authors.initials: T
authors.lastname: Elbert
authors.forename: Michael
authors.initials: M
authors.lastname: Przybylski
authors.forename: Iris-Tatjana
authors.initials: IT
authors.lastname: Kolassa
authors.forename: Marilena
authors.initials: M
authors.lastname: Manea
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis*; D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000276:immunology*; D000936:Antigen-Antibody Complex / Q000097:blood; D001323:Autoantibodies / Q000097:blood; D060825:Cognitive Dysfunction / Q000097:blood / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000939:Epitopes / Q000235:genetics; D005260:Female; D005858:Germany; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009483:Neuropsychological Tests
chemical_list: D016229:Amyloid beta-Peptides; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D000939:Epitopes; D007074:Immunoglobulin G