Fig. 3.

FSB does not bind to the antibodies, and its staining of histological brain sections reveals colocalization with the injected tau antibody.

a. Compared to positive FSB control, the tau antibodies 4E6 and 6B2 or control IgG1 do not bind to FSB on ELISA plates. This indicates that the colocalization of FSB with the antibodies observed in vivo is not due to non-specific interactions.

b. After the last imaging session at 7 days, fixed htau/PS1 brain sections from FSB + 4E6 injected htau/PS1 mouse were restained with FSB (green) because it clears during the standard defatting and rehydration procedure. The image shows its partial colocalization with injected Alexa-568 labeled 4E6 (red). c. Staining of fixed htau/PS1 brain sections from an untreated control htau/PS1 mouse shows partial co-localization of FSB (green) with phospho-tau antibody PHF1 (red), indicating that FSB can bind to pathological phospho-tau protein. Scale bar = 10 µm. All data are presented as mean + SEM.