A streamlined, resource-efficient immunoprecipitation-mass spectrometry method for quantifying plasma amyloid-ß biomarkers in Alzheimer's disease.

ABSTRACT

High-performance, resource-efficient methods for plasma amyloid-ß (Aß) quantification in Alzheimer's disease are lacking; existing mass spectrometry-based assays are resource- and time-intensive. We developed a streamlined mass spectrometry method with a single immunoprecipitation step, an optimized buffer system, and ≤75% less antibody requirement. Analytical and clinical performances were compared with an in-house reproduced version of a well-known two-step assay. The streamlined assay showed high dilution linearity (r2>0.99) and precision (< 10% coefficient of variation), low quantification limits (Aß1-40 12.5 pg/ml; Aß1-42 3.125 pg/ml), and high signal correlation (r2~0.7) with the two-step immunoprecipitation assay. The novel single-step assay showed more efficient recovery of Aß peptides via fewer immunoprecipitation steps, with significantly higher signal-to-noise ratios, even at plasma sample volumes down to 50 pl. Both assays had equivalent performances in distinguishing non-elevated vs. elevated brain Aß-PET individuals. The new method enables simplified yet robust evaluation of plasma Aß biomarkers in Alzheimer's disease.