Enolase isoenzyme distribution in the human brain and its tumours

Using the immunoperoxidase PAP method we have studied the cellular distribution of alpha, beta and gamma enolase subtypes in normal human adult brain and in human brain neoplasms. Gamma enolase is found only in viable neurones throughout the brain. Alpha enolase is demonstrable in astrocytes, ependymal cells, capillary endothelial cells. Schwann cells and arachnoidal endothelial cells but oligodendrocytes appear to have low levels of this isoenzyme. Beta enolase is not demonstrable in normal brain tissues. Of the primary cerebral neoplasm studied only medulloblastomas and neuroblastomas did not contain demonstrable enolase. Astrocytomas, ependymomas, oligodendrocytomas, meningiomas and acoustic neuromas all contained varying quantities of alpha enolase. No cerebral tumours contained beta or gamma enolase. Tumour and adjacent brain tissue with histological evidence of ischaemia and necrosis showed loss of cellular enolase.