A human mAb generated against a non-amyloid target binds aggregated Aβ.

<p>(<b>A</b>) Left panel: SEC chromatograms for ~15 mg/mL of mAb Avastin (anti-VEGF) and IVIg. SEC was carried out using a Superdex 200 Increase 10/300 GL column (GE Healthcare) equilibrated in PBS, pH 7.4. Right panel: Antibody binding curves against plate-immobilized PFs for unfractionated (Unfrac) IVIg, and for Avastin used unfractionated or as SEC-isolated monomers and dimers. (<b>B</b>) The top Western blots show immunoprecipitation (IP) of synthetic Aβ conformers (monomers (Mon), dimers, and PFs) by 100 μg/mL of Avastin and IVIg, and by 200 μg/mL of a pan-Aβ reactive polyclonal antibody, AW8. The blots were probed for Aβ using an Aβ N-terminal reactive mAb, 6E10 (Signet Laboratories). The lower Western blots show 20 μg/mL mAb Avastin's ability to IP 5 μg/mL of Aβ dimers and PFs in the presence of a 5-molar excess (with respect to Avastin) of a N-terminal 165-amino acid fragment of its immunogen VEGF (VEGF-165). Control IP experiments (Ctls) were carried out using 5 μg/mL mAb 6E10 and a mixture of Aβ dimers and PFs, or with 20 μg/mL Avastin and 1 μg/mL VEGF-165. The blots were probed for Aβ and VEGF-165 using mAb 6E10 and Avastin, respectively. In IPs carried out in the absence of VEGF-165, cross-reactivity of the secondary antibody, goat anti-human IgG (heavy and light, Jackson Immunoresearch Laboratories Inc), with Avastin’s Ig light chain caused a faint band that migrated near VEGF-165. (<b>C</b>) Avastin IgG conformers binding curves against plate-immobilized PFs in the presence or absence of a 1:10 dilution of IgG-depleted normal human sera. (<b>D</b>) Bar charts for solution-phase PF's, Aβ monomers, and non-amyloid native and aggregated molecule's inhibition of Avastin monomers an dimers binding to plate-immobilized PFs. Competition studies were carried out using 0.1 mg/mL competitors and concentrations of Avastin conformers that were equivalent to their EC₅₀ values for PFs: 500 nM IgG Mon, and 200 nM IgG dimer. Each competition curve was carried out in duplicate, and bars represent the standard error.