Fig. 2

DC8E8 antibody and AADvac1-induced DC8E8-like antibodies promote tau uptake into primary mouse microglia. Increased amount of tau was detected in microglia incubated with fluorescently labelled oligomerized tau151–391/4R in the presence of DC8E8 in comparison to microglia incubated with tau alone or with tau in the presence of control monoclonal antibody DC51. a Tau uptake after 20 min incubation was quantified as mean fluorescence intensity using flow cytometry and normalized relative to tau only (tau vs tau+DC8E8, ****p < 0.0001, n = 10; tau vs tau+DC51, p = 0.9227, n = 4; tau+DC8E8 vs tau+DC51, ****p < 0.0001, n = 4), one-way ANOVA, Tukey’s multiple comparisons was used for statistical evaluation. b DC8E8-enhanced tau uptake by microglia was confirmed by immunostaining. Representative fluorescent photomicrographs show increased amount of Tau (green) within microglia after 20 min incubation with tau and DC8E8. Cell nuclei were stained with DAPI (blue). Scale bars, 10 μm. c Monoclonal profile of DC8E8 and polyclonal character of AADvac1-induced tau-specific antibodies and control sera antibodies stained with Coomasie Blue. d Similar tau-binding capacity of antibodies DC8E8 and AADvac1-induced tau-specific antibodies. Negative tau-binding potential of control sera antibodies was detected by sandwich enzyme-linked immunosorbent assay. e Serum antibodies generated after AADvac1 vaccination in mice (AADvac1-Abs) showed similar functional properties as DC8E8 antibody in primary mouse microglia. AADvac1-Abs significantly promote uptake of oligomerized tau151–391/4R into primary microglia (tau vs tau+AADvac1-Abs, **p < 0.0031, n = 10; tau vs tau+ctrl serum-Abs, p = 0.9998, n = 5; tau+AADvac1-Abs vs tau+ctrl serum-Abs, *p < 0.0154, n = 5), one-way ANOVA, Tukey’s multiple comparisons was used for statistical evaluation