High precision and cost-effective multiplex quantification of amyloid-β40, amyloid-β42, p181Tau, p217Tau, neurofilament light chain, and glial fibrillary acidic protein from plasma and serum

Background Current methods to quantify blood biomarkers for Alzheimer's disease (AD) are expensive and are not widely available. Objective To develop a low-cost, sensitive, and accurate multiplex assay to quantify Aβ 40 , Aβ 42 , p181Tau, p217Tau, NfL, and GFAP biomarkers in plasma and serum based on a widely available technology. Methods We used commercial antibodies to Aβ 40 , Aβ 42 , p181Tau, p217Tau, NfL, and GFAP, and xMAP Luminex technology, and developed the multiplex 5ADCSI to quantify these biomarkers from plasma and serum. The utility of 5ADCSI was tested in matched cerebrospinal fluid (CSF) and plasma or serum of a cohort of cognitively normal (CN: n = 35), with mild cognitive impairment (MCI: n = 17), and with AD (n = 11) individuals. Results The 5ADCSI demonstrated high specificity and sensitivity, with excellent precision. In clinical samples, moderate to strong correlation is observed between CSF and plasma or serum for Aβ 42/40 ( r = 0.78 ), p181Tau/Aβ 42 ( r = 0.57 ), p217Tau/Aβ 42 ( r = 0.72 ), p181Tau ( r = 0.59 ), p217Tau ( r = 0.75 ), and GFAP ( r = 0.59 ). The AUC of receiver-operator characteristic curve for differentiating CN from AD for plasma/serum and CSF are 0.75, and 0.80 for Aβ 42/40 , 0.95, 0.91 for p217Tau, 0.76, 0.81 for p181Tau, and 0.73 and 0.78for GFAP, respectively. Conclusions The 5ADCSI assay is highly specific, sensitive, and accurate. The wide availability of the base technology of 5ADCSI is an advantage over other similar methods and would allow cost-effective large-scale studies for validation of blood biomarkers for early diagnosis of AD.