Glial swelling with eosinophilia in human post-mortem brains: a change indicative of plasma extravasation

Swollen, intensely eosinophilic glial cells are often observed in the vicin ity of hemorrhagic lesions in post-mortem human brains. We sought to determ ine the nature of this change. Thirty adult human brains removed at autopsy and three surgical specimens were obtained 6h to 60 days following a hemor rhagic event. They were subjected to a battery of histochemical and immunoh istochemical stains. The swollen cells, which were observed in the majority of autopsy specimens in which hemorrhage had occurred within the previous 9 days, stained intensely red with Masson stain and were immunoreactive for IgG, IgM, IgA, and fibrinogen. Some were also immunoreactive for glial fib rillary acidic protein, particularly in subpial and subependymal areas, if the lesions were more than 3 days old. In white matter some of the cells we re immunoreactive for CNPase. There was no labeling with markers for macrop hage/microglial cells. The absence of DNA fragment detection by TUNEL sugge sts that the cells were not dying. Mild glial cytoplasmic eosinophilia with out swelling was observed in surgical specimens. No eosinophilic swollen gl ia were seen in perfusion-fixed rat brains with experimental intracerebral hemorrhage, although they were seen in rat brains that were not promptly fi xed. We conclude that human macroglia, including astrocytes and oligodendro cytes, ingest plasma proteins that have been released into brain parenchyma . This likely represents a homeostatic mechanism that maintains the composi tion of the extracellular environment. If the tissue is not promptly fixed the cells become more swollen and eosinophilic.