Amyloid β peptides are differentially vulnerable to preanalytical surface exposure, an effect incompletely mitigated by the use of ratios

Use of Aβ ratios, in conjunction with concentrations, may mitigate confounding factors and assist the clinical diagnostic process for Alzheimer's disease.

Human cerebrospinal fluid (CSF) and culture media (CM) from human cortical neurons were exposed to a series of volumes and polypropylene surfaces. Aβ42, Aβ40, and Aβ38 peptide concentrations were measured using a multiplexed electrochemiluminescence immunoassay. Data were analyzed using mixed models in R.

Decrease of measurable Aβ peptide concentrations was exaggerated in longer peptides, affecting the Aβ42:Aβ40 and Aβ42:Aβ38 ratios. However, the effect size of surface treatment was reduced in Aβ peptide ratios versus Aβ42 alone. For Aβ42:Aβ40, the effect was reduced by approximately 50% (volume) and 75% (transfer) as compared to Aβ42 alone.