Preparation and Characterization of a Monoclonal Antibody with High Affinity for Soluble Aβ Oligomers

Amyloid β-protein (Aβ) has been causally implicated in the neurodegenerative processes that accompany Alzheimer's disease. Soluble oligomers of the Aβ 1-42 fragment are thought to be significantly more neurotoxic than higher molecular weight aggregates. We report the isolation and characterization of a mouse monoclonal antibody (MAb) directed against soluble Aβ 1-42 oligomers. Synthetic Aβ 1-42 oligomers were assembled in vitro ; these were used to immunize mice, and hybridomas were isolated following myeloma fusion of splenocytes from immunized animals. Screening for reactivity against Aβ 1-42 resulted in the identification of MAb A8 with high affinity for soluble oligomers. The isotype of A8 was found to be IgG 2b . Experiments using sub-peptides of Aβ 1-42 revealed that the epitope identified by A8 lies within the 1–6 region of Aβ. The antibody displays high affinity for soluble Aβ 1-42 oligomers in the molecular weight range of 16.5–25 kDa, and detected target antigen in brain sections from senescence-accelerated SAMP 8 mice. The sensitivity and optimal titers for the detection of soluble Aβ 1-42 oligomers were determined to be 0.625 μg/mL in indirect ELISA, and 1:10 6 , 1:4000, and 1:150 for ELISA, Western blotting, and immunohistochemistry, respectively. The A8 antibody specific for soluble Aβ 1-42 oligomers will provide a valuable tool for Alzheimer's disease research.