An ultra-sensitive immunoassay detects and quantifies soluble Aß oligomers in human plasma.

ABSTRACT

INTRODUCTION: Evidence strongly suggests that soluble oligomers of amyloid beta protein (oAß) help initiate the pathogenic cascade of Alzheimer's disease (AD). To date, there have been no validated assays specific for detecting and quantifying oAß in human blood. METHODS: We developed an ultrasensitive oAß immunoassay using a novel capture antibody (71A1) with N-terminal antibody 3D6 for detection that specifically quantifies soluble oAß in the human brain, cerebrospinal fluid (CSF), and plasma. RESULTS: Two new antibodies (71A1; 1G5) are oAß-selective, label Aß plaques in non-fixed AD brain sections, and potently neutralize the synaptotoxicity of AD brain-derived oAß. The 71A1/3D6 assay showed excellent dilution linearity in CSF and plasma without matrix effects, good spike recovery, and specific immunodepletion. DISCUSSION: We have created a sensitive, high throughput, and inexpensive method to quantify synaptotoxic oAß in human plasma for analyzing large cohorts of aged and AD subjects to assess the dynamics of this key pathogenic species and response to therapy.