Simultaneous expression of glial fibrillary acidic (GFA) protein and neuron-specific enolase (NSE) by the same reactive or neoplastic astrocytes.

In normal cells of the central nervous system (CNS), glial fibrillary acidic (GFA) protein is demonstrable by immunohistochemistry in fibrillated astrocytes, and neuron-specific enolase (NSE) in neurons and their processes. However, it has been shown that NSE may also be expressed in reactive astrocytes and in various neoplastic cells of non-neuronal origin, including those of astrocytomas and glioblastomas. In the present study, a double-labelling technique using immunoperoxidase (PAP) and immunofluorescence (FITC) was employed to determine whether GFA protein and NSE could be expressed simultaneously by the same cell. This was found to be the case in some, but not in all reactive astrocytes in the human brain. In glial tumours, many of the neoplastic cells in the glioblastomas and astrocytomas examined demonstrated either GFA protein or NSE, but usually not both. However, occasional neoplastic cells in those gliomas were found to show both proteins. Because of the relatively low sensitivity of the FITC technique, the percentage of cells expressing both proteins could not be determined, but it is clearly possible for a single reactive or neoplastic astrocyte to demonstrate both GFA protein and NSE.