Figure 1.

The 19.3 antibody selectively binds to oligomeric Aβ. The differential binding of the 19.3 antibody to Aβ monomer and oligomers was quantified in (A) a one-site ELISA and in (B) a competitive binding ELISA. In the one-site ELISA, 19.3 showed only a modestly different EC₅₀ for monomer (0.64 pg/ml, ■) and Aβ oligomers (0.25 pg/ml, ▴). The maximal binding was greater for Aβ oligomers. In the competitive binding ELISA, 39 ng/ml of Aβ oligomers was sufficient to displace 50% binding to coated Aβ40 monomers (■), whereas 24.8 μg/ml Aβ monomer was needed to displace 50% of the Aβ oligomer (▴) binding. RLU, relative luminescence units.