title: A sensitive aβ oligomer assay discriminates Alzheimer's and aged control cerebrospinal fluid.
abstract: A hallmark of Alzheimer's disease (AD) brain is the amyloid β (Aβ) plaque, which is comprised of Aβ peptides. Multiple lines of evidence suggest that Aβ oligomers are more toxic than other peptide forms. We sought to develop a robust assay to quantify oligomers from CSF. Antibody 19.3 was compared in one-site and competitive ELISAs for oligomer binding specificity. A two-site ELISA for oligomers was developed using 19.3 coupled to a sensitive, bead-based fluorescent platform able to detect single photons of emitted light. The two-site ELISA was >2500× selective for Aβ oligomers over Aβ monomers with a limit of detection ∼ 0.09 pg/ml in human CSF. The lower limit of reliable quantification of the assay was 0.18 pg/ml and the antibody pairs recognized Aβ multimers comprised of either synthetic standards, or endogenous oligomers isolated from confirmed human AD and healthy control brain. Using the assay, a significant 3- to 5-fold increase in Aβ oligomers in human AD CSF compared with comparably aged controls was demonstrated. The increase was seen in three separate human cohorts, totaling 63 AD and 54 controls. CSF oligomers ranged between 0.1 and 10 pg/ml. Aβ oligomer levels did not strongly associate with age or gender, but had an inverse correlation with MMSE score. The C statistic for the Aβ oligomer ROC curve was 0.86, with 80% sensitivity and 88% specificity to detect AD, suggesting reasonable discriminatory power for the AD state and the potential for utility as a diagnostic marker.
authors.affiliation: Department of Molecular Biomarkers, Department of Neuroscience, and Department of Pharmacology, Merck & Company, Inc., West Point, Pennsylvania 19486.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Savage
authors.forename: Juliya
authors.initials: J
authors.lastname: Kalinina
authors.forename: Abigail
authors.initials: A
authors.lastname: Wolfe
authors.forename: Katherine
authors.initials: K
authors.lastname: Tugusheva
authors.forename: Rachel
authors.initials: R
authors.lastname: Korn
authors.forename: Tanesha
authors.initials: T
authors.lastname: Cash-Mason
authors.forename: Jill W
authors.initials: JW
authors.lastname: Maxwell
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Hatcher
authors.forename: Sharie J
authors.initials: SJ
authors.lastname: Haugabook
authors.forename: Guoxin
authors.initials: G
authors.lastname: Wu
authors.forename: Bonnie J
authors.initials: BJ
authors.lastname: Howell
authors.forename: John J
authors.initials: JJ
authors.lastname: Renger
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Shughrue
authors.forename: Alexander
authors.initials: A
authors.lastname: McCampbell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000134:cerebrospinal fluid*; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000175:diagnosis* / Q000523:psychology; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000276:immunology; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D015415:Biomarkers / Q000134:cerebrospinal fluid; D004797:Enzyme-Linked Immunosorbent Assay; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000134:cerebrospinal fluid; D012372:ROC Curve; D015203:Reproducibility of Results; D012542:Scattering, Radiation
chemical_list: D016229:Amyloid beta-Peptides; D000906:Antibodies; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)
keywords: Abeta oligomer; Alzheimer