Fig. 3

4E6, but not 6B2, reduced soluble phospho-tau levels in htau mice. a, b Insoluble tau protein (sarkosyl pellet) levels were not altered in a 4E6 or b 6B2 immunized mice as detected by total human tau antibody CP27, compared to IgG controls. Similar results were obtained with total tau antibody Tau-5 or phospho-tau antibody PHF-1 (not shown, see values in text). c–f Likewise, soluble tau levels (low speed supernatant; CP27, Tau-5) normalized to GAPDH were not significantly altered in 4E6 treated mice compared to IgG control group. g, h Animals treated with 4E6 showed a significant reduction in levels of soluble PHF-1 reactive tau relative to IgG controls (48 % reduction, p = 0.037), while those treated with 6B2 showed no change. This beneficial effect of the therapy was not gender related (two-way ANOVA; gender effect: p = 0.905). i Also, the cognitive benefits in the 4E6 group could not be explained by differences in T22 detected oligomeric tau as those levels did not differ between the 4E6 and IgG group (dot blot quantitation shown, similar results were seen on Western blots (not shown). *: p < 0.05