Progressive supranuclear palsy with hypertrophy of the olives. An immunocytochemical study of the cytoskeleton of argyrophilic neurons.

In a patient with progressive supranuclear palsy (PSP) and hypertrophy of the olives, neurons with different forms of argyrophilic degeneration were detected by means of Bodian's silver staining method, i.e., neurofibrillary tangle-bearing neurons in the basal ganglia and brain stem, ballooned argyrophilic neurons in the brain stem, and hypertrophied neurons in the olives. In these cells, the cytoskeleton was investigated to ascertain whether neurons with different cytoskeletal changes contained phosphorylated neurofilaments (P-Nf) in the perikaryon. This study, carried out using two monoclonal antibodies that recognize phosphorylated epitopes of the neurofilament high molecular weight subunits, showed that hypertrophied olivary neurons, most ballooned neurons and a small aliquot of tangle-bearing neurons were labelled. The immunostaining of hypertrophied and ballooned neurons was localized in the whole perikaryon and dendrites, whereas that of tangle-bearing neurons was confined to the tangle. These findings were reproduced in five additional patients (one with hypertrophy of the olives, four with PSP) and demonstrated that, in PSP, the mechanism responsible for tangle formation does not affect the ability of neurons to accumulate P-Nf. This fact suggested that perikaryonal P-Nf accumulation is likely to be part of the cell reaction to abnormal conditions affecting the neuronal cytoskeleton.