Fig. 1

Immunodepletion of pooled CSF to remove tau using a combination of antibodies targeting the N terminus, mid region, and C terminus of tau. a. Pooled human CSF from multiple de-identified patients (CSF-tau) was divided into 3 aliquots. An aliquot of the pooled CSF-tau sample was immuno-depleted for tau by the simultaneous application of the monoclonal antibodies Tau12, HT7 and TauAB (epitopes: amino acids 6–18, 159–163 and 425–441, respectively) that together cover nearly the entire tau-441 protein sequence using published protocols [79], this is referred to herein as CSF-tau-depleted. The second aliquot remained the full sample, referred to as CSF-tau. The final aliquot underwent the same immunodepletion protocol with different antibodies (anti-mouse IgG and neurogranin (H-6) antibody) to provide a control for the tau immunodepletion, referred to as CSF-mock-depletion. b, To verify the removal of tau after the immuno-depletion in aliquot 1, t-tau assay from Quanterix, p-tau181 [75] and p-tau231 [8] in house assays were used for tau measurements in the CSF-depleted and non-depleted aliquots and compared in parallel against the CSF-mock-depleted sample on a Simoa HD-X instrument (Quanterix, Billerica, MA, USA) following methods originally described in the cited publications. c, The immunodepletion of tau was further validated by comparison to the full CSF sample using fully automated Lumipulse (Fujirebio) platform following published protocols [49]