Oligomer-specific ELISA specifically detects human amyloid-beta species in AD-TBS brain extracts. Soluble extracts of Alzheimer’s disease (AD) brains 1 to 4 (A) and brains 5 to 9 (B) were serially diluted and assayed with the Erenna 1C22/3D6 oligomer-specific enzyme-linked immunosorbent assay (o-ELISA), revealing highly linear concentration curves in the extracts of all brains. SAT, o-ELISA value of the highest loaded standard (50 pg/ml). (C) After pre-clearing with plain beads, AD-TBS extracts of brains 5 to 9 were each subjected to sequential IPs with amyloid-beta antisera 1282 and AW7, and the resultant supernatants assayed by o-ELISA. Western blotting (inset: monoclonal antibodies 6E10 + 2G3 + 21 F12) of a representative immunodepletion experiment shows: lane 1, starting AD extract; lane 2, its supernatant after 1282 + AW7 immunodepletion; and lane 3, IP’ed 1282 + AW7 pellet. TBS, Tris-buffered saline (20 mM Tris–HCl, pH 7.4, containing 150 mM NaCl). Erenna platform (Singulex, Alameda, CA, USA).