Analysis of size exclusion chromatography-fractioned ADDLs reveals that the oligomer-specific ELISA detects a range of different sized amyloid-beta assemblies but not monomers. The amyloid-beta-derived diffusible ligand preparation was chromatographed on a Superdex 200 10/30 HR column (GE Healthcare Biosciences, Pittsburgh, PA, USA) by eluting in sodium phosphate buffer at 0.5 ml/minute. Absorbance at 214 nm was recorded, and 0.5 ml fractions were collected and analyzed by the 1C22/3D6 Erenna oligomer-specific enzyme-linked immunosorbent assay (o-ELISA). All fractions were diluted 5 × 105-fold prior to o-ELISA. Elution positions of Blue Dextran and globular standards are indicated by arrows and molecular weights (kDa). oAβ, amyloid-beta oligomers. Erenna platform (Singulex, Alameda, CA, USA).