Sensitive ELISA detection of amyloid-beta protofibrils in biological samples.
Amyloid-beta (Abeta) protofibrils are known intermediates of the in vitro Abeta aggregation process and the protofibrillogenic Arctic mutation (APPE693G) provides clinical support for a pathogenic role of Abeta protofibrils in Alzheimer's disease (AD). To verify their in vivo relevance and to establish a quantitative Abeta protofibril immunoassay, Abeta conformation dependent monoclonal antibodies were generated. One of these antibodies, mAb158 (IgG2a), was used in a sandwich ELISA to specifically detect picomolar concentrations of Abeta protofibrils without interference from Abeta 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 and Arctic mutation in combination. The mAb158 sandwich ELISA analysis revealed presence of Abeta protofibrils in both cell and animal models, proving that Abeta protofibrils are formed not only in vitro, but also in vivo. Furthermore, elevated Abeta 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 Abeta protofibrils in AD and has the potential of becoming an important diagnostic assay.
Englund
Hillevi
H
Department of Public Health/Molecular Geriatrics, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Sehlin
Dag
D
Johansson
Ann-Sofi
AS
Nilsson
Lars N G
LN
Gellerfors
Pär
P
Paulie
Staffan
S
Lannfelt
Lars
L
Pettersson
Frida Ekholm
FE
D000544:Alzheimer Disease / Q000175:diagnosis / Q000378:metabolism; D000682:Amyloid / Q000032:analysis*; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D012680:Sensitivity and Specificity
D000682:Amyloid; D016564:Amyloid beta-Protein Precursor; D000911:Antibodies, Monoclonal