A Luminex assay detects amyloid ß oligomers in Alzheimer's disease cerebrospinal fluid.

ABSTRACT

Amyloid beta (aß) protein assembles into larger protein aggregates during the pathogenesis of Alzheimer's disease (AD) and there is increasing evidence that soluble aß oligomers are a critical pathologic species. Diagnostic evaluations rely on the measurement of increased tau and decreased aß42 in the cerebrospinal fluid (CSF) from AD patients and evidence for oligomeric aß in patient CSF is conflicting. In this study, we have adapted a monoclonal single antibody sandwich ELISA assay to a Luminex platform and found that this assay can detect oligomerized aß42 and sAPPα fragments. We evaluated oligomeric aß reactivity in 20 patients with AD relative to 19 age matched controls and compared these values with a commercially available Alzbio3 kit that detects tau, phosphorylated tau and aß42 on the same diagnostic platform. We found that CSF samples of patients with AD had elevated aß oligomers compared to control subjects (p < 0.05) and the ratio of aß oligomers to aß42 was also significantly elevated (p < 0.0001). Further research to develop high sensitivity analytical platforms and rigorous methods of developing stable assay standards will be needed before the analysis of oligomeric aß becomes a routine diagnostic assay for the evaluation of late onset AD patients.