Sensitive ELISA detection of amyloid-β protofibrils in biological samples

Amyloid-beta (A beta) protofibrils are known intermediates of the in vitro A beta aggregation process and the protofibrillogenic Arctic mutation (APPE693G) provides clinical support for a pathogenic role of A beta protofibrils in Alzheimer's disease (AD). To verity their in vivo relevance and to establish a quantitative A beta protofibril immunoassay, A beta conformation dependent monoclonal antibodies were generated. One of these antibodies, mAb158 (IgG2a), was used in a sandwich ELISA to specifically detect picomolar concentrations of A beta protofibrils without interference from A beta monomers or the amyloid precursor protein (APP). The specificity and biological significance of this ELISA was demonstrated using cell cultures and transgenic mouse models expressing human APP containing the Swedish mutation (APPKN670/671ML), or the Swedish Amyloid-P (A beta) protofibrils are known intermediates of the and Arctic mutation in combination. The mAb158 sandwich in vitro A beta aggregation process and the protofibrillogenic ELISA analysis revealed presence of A beta protofibrils in both Arctic mutation (APPE693G) provides clinical support for a pathogenic role of A beta protofibrils in Alzheimer's disease (AD). To verity their in vivo relevance and to establish a quantitative A beta protofibril immunoassay, A beta conformation dependent monoclonal antibodies were generated. One of these antibodies, mAb158 (IgG2a), was used in a sandwich ELISA to specifically detect picomolar concentrations of A beta protofibrils without interference from A beta monomers or the amyloid precursor protein (APP). The specificity and biological significance of this ELISA was demonstrated using cell cultures and transgenic mouse models expressing human APP containing cell and animal models, proving that A beta protofibrils are formed not only in vitro, but also in vivo. Furthermore, elevated A beta protofibril levels in the Arctic-Swedish samples emphasize the usefulness of the Arctic mutation as a model of enhanced protofibril formation. This assay provides a novel tool for investigating the role of A beta protofibrils in AD and has the potential of becoming an important diagnostic assay.