The difference in immunohistochemical reactivity of monoclonal antibodies against amino-terminal residues of amyloid-β peptide

Immunohistochemistry for amyloid-β (Aβ) peptide is an indispensable method for Alzheimer’s disease (AD) research. Despite a wide variety of available antibodies against the peptides, the difference of immunohistochemical reactivity is not fully described among anti-Aβ antibodies. Immunohistochemical reactivity of Abs against Aβ peptides is critical for accurate and reliable evaluation of Aβ burden in patients as well as models of AD. Here, we examined immunohistochemical reactivity of two mouse and one rabbit monoclonal antibodies against Aβ N-terminal regions using two AD mouse models, App ^NL-F and App ^NL-G-F . 6E10, 82E1 and D54D2 Aβ antibodies were used in this study. We found significant differences in the immunohistochemical reactivity in both App ^NL-F and App ^NL-G-F models. While 6E10 immunoreactivity was mainly localized to Aβ plaques, D54D2 and 82E1 antibodies stained much more broadly beyond plaques. Interestingly, the latter two Abs showed blurred filamentous immunoreactivity beyond amyloid plaque cores. Double immunostaining using a tyramide signal amplification method, Fluorochromized Tyramide-Glucose Oxidase (FT-GO), suggested that the differential immunohistochemical outcomes were only partially attributable to their sensitivity. Moreover, heat induced epitope retrieval (HIER) did not affect the differential immunohistochemical outcomes. Our analysis indicates that outcomes of Aβ immunohistochemistry highly depends on the antibody used in the study.