Monoclonal antibody DC8E8 inhibits pathological tau–tau interaction. (A) Inhibition of pathological tau–tau interaction by DC8E8. The amount of oligomerised tau (297-391/4R) was measured by thioflavin T fluorescence in the absence and in the presence of the monoclonal antibody (mAb) DC8E8 at the time points 1, 4 and 20 hours. Inhibitory activity of DC8E8 was statistically significant for the indicated time points when analysed using a nonparametric t-test (P < 0.0001). (B) Analysis of the inhibitory potential of DC8E8 showing prevention of the formation of tau dimers, trimers and oligomers by mis-disordered truncated tau by immunoblotting using horseradish peroxidase–conjugated mAb DC25. The positions of the molecular weight markers are indicated on the right.