Immunocytochemical and ultrastructural studies of neuronal and oligodendroglial cytoplasmic inclusions in multiple system atrophy. 2. Oligodendroglial cytoplasmic inclusions.

Oligodendroglial cytoplasmic inclusions (OCI) in multiple system atrophy were investigated immunocytochemically and ultrastructurally. Among the 17 cases examined, 16 had OCIs. Almost all OCIs were positive for both alpha B-crystallin and ubiquitin. The antibodies against tubulin, paired helical filament and tau stained OCIs to various extents. Ultrastructurally OCIs consisted of meshworks of granule-associated filaments about 25 nm in diameter that sometimes formed flame-shaped tangle-like structures. Immunoelectron microscopy showed that an epitope of alpha B-crystallin was located on the granule-associated filaments composing OCIs. Our studies further support a cooperative role of alpha B-crystallin, ubiquitin and cytoskeletal protein in the formation of some types of intracytoplasmic inclusions.