Further observations on Tau-positive glia in the brains with progressive supranuclear palsy

The previously reported unusual, Tau-positive glia with astrocytic morphology seen in brain tissues from cases of progressive supranuclear palsy (PSP) were re-examined immunohistochemically using antibodies to CD44 and vimentin, as well as Alz-50. Four brains of PSP cases, one of whom had atypical clinical features, were examined. All four cases showed the unusual glia which were positive to Alz-50 and anti-CD44 antibodies, but negative to anti-vimentin antibody. Ultrastructurally, they had either paired nucleated or lobulated nuclei and the cytoplasm frequently contained lipofuscin pigment. The CD44 was located on the surface of the cell bodies and their processes. Such glia were most numerous in the striatum in all cases. They also appeared in the cortex and some subcortical nuclei in the three typical cases. They were not seen in the lower brain stem or cerebellum. In their morphological characteristics and regionally specific appearance, these unusual glia seemed similar to the Alzheimer type I glia which are commonly seen in hepatic encephalopathy or Wilson's disease.