Immunohistochemical study of tau isoforms in sporadic tauopathies

Mari Yoshida

Department of Neuropathology, Institute for Medical Science of Aging Aichi Medical University

　　To better define the tau isoform composition in sporadic tauopathies, we investigated immunohistochemistry of 2 cases with Alzheimer’s disease (AD), 2 cases with diffuse neurofibrillary tangles with calcification (DNTC), 4 cases with Pick's disease with Pick bodies (PiD), 7 cases with progressive supranuclear palsy (PSP), 6 cases with corticobasal degeneration (CBD) and 7 cases with argyrophilic grain dementia (AGD).　We used two monoclonal antibodies, RD3, RD4, and a polyclonal antibody for exon 10 that effectively distinguish between three-repeat (3R) tau and four-repeat (4R) tau.
　　Neuronal neurofibrillary tangles (NFTs) and neuropil threads (NTs) in AD and DNTC contained 3R-tau and less amount of 4R-tau, in contrast extraneuronal NFTs indicated 3R-tau predominantly.　The Pick bodies were predominantly immunopositive for 3R-tau in two cases, but in another two cases they were immunopositive for 4R-tau.　Thus Pick bodies demonstrated heterogeneity.　In PSP and CBD, both neuronal and glial tau accumulation forming NFTs, pretangles, tuft-shaped astrocytes, astrocytic plaques, coiled bodies and threads demonstrated 4R-tau in the cerebral cortices, although in basal ganglia and brainstem neuronal and glial inclusions were occasionally immunopositive for 3R-tau in addition to 4R-tau in several cases.　AGs were immunopositive for 4R-tau.　Therefore the isoform composition showed heterogeneity in PiD, and it was not uniformity in basal ganglia and brain stem in PSP and CBD.

Address correspondence to Dr. Mari Yoshida, Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University (Nagakute-cho, Aichi-gun, Aichi 480-1195, Japan)