Quantification of tau phosphorylated at threonine 181 in human cerebrospinal fluid : a sandwich ELISA with a synthetic phosphopeptide for standardization

Abstract Hyperphosphorylation of the microtubule-associated protein tau is specifically found in those brain cells affected in several tauopathies. Tau has also been consistently found to be present in the cerebrospinal fluid (CSF). Here we report the quantification in CSF of tau phosphorylated at Thr 181 using an immunoassay with a synthetic peptide for standardization. The choice of the peptide was based on fine mapping of a phospho-dependent antibody, AT270 (P 176 PAPKT p P 132 )and a human specific tau antibody, HT7 (P 159 PGQK 163 ). CSF-phospho-tau levels were increased in Alzheimer patients (23.5±10.1 pM, P P r 2 =0.73; frontotemporal dementia, r 2 =0.43; Control, r 2 =0.42), suggesting that the degree of phosphorylation of CSF-tau changes in different clinical conditions.