Argyrophilic glial inclusions in the midbrain of patients with Parkinson's disease and diffuse Lewy body disease are immunopositive for NACP/alpha-synuclein.

Argyrophilic glial inclusions occur in the midbrain of patients with Parkinson's disease (PD) and diffuse Lewy body disease (DLBD). These inclusions are immunohistochemically positive for NACP/alpha-synuclein but negative for tau protein. The results of the present study suggest that a primary degenerative process involves NACP/alpha-synuclein in PD and DLBD and that the process takes place not only in neurons but also in glial cells. Argyrophilic cytoplasmic inclusions, both glial and neuronal, in a variety of degenerative diseases may be grouped into two major categories; one related to aggregates of abnormally phosphorylated tau protein and the other to unusual accumulations of NACP/alpha-synuclein.