Nerve cells expressing heat-shock proteins in Parkinson's disease

A distinctive histopathological feature of several neurodegenerative diseases, including corticobasal degeneration, argyrophilic grain disease, progressive supranuclear palsy, and Pick's disease, are achromatic nerve cells that express small heat-shock proteins, such as αB-crystallin or hsp-27, and develop in specific telencephalic cortical areas and subcortical nuclei. Here, we point to the consistent presence of such cells in Parkinson's disease. In this disorder, the neurons under consideration remain immunonegative for phosphorylated neurofilaments or for ubiquitin, thus exhibiting an immunocytochemical profile different from that shown by αB-crystallin-positive neurons in other neurodegenerative disorders. In severe cases of Parkinson's disease, the αB-crystallin-positive neurons are dispersed throughout the cerebral cortex, amygdala, and ventral claustrum. In cases showing relatively mild involvement of the telecephalon, these neurons occur chiefly within the reaches of the anterior temporal and insular mesocortex. These telencephalic predilection sites are nearly identical with those of the α-synuclein pathology. Nevertheless, most of the telencephalic αB-crystallin-immunopositive neurons refrain from developing Lewy bodies and Lewy neurites and, vice versa, most of the nerve cells containing Lewy bodies do not accumulate αB-crystallin.