Activated rat peritoneal mast cells can cause syngeneic brain demyelination in vitro

Mast cells exist primarily in connective tissues where they participate in allergic reactions by secreting numerous vasoactive, chemotactic and degredative substances. Mast cells are also found perivascularly on the dura, the choroid plexus, the thalamus and hypothalamus, among other regions of the brain. Here we report the effect of unpurified rat peritoneal mast cells, activated by their classic secretagogue compound 48/80 (C48/80), on syngeneic rat brain slices during overnight incubation. Brain sections were also exposed to medium containing only C48/80, while yet others to medium enriched with the supernatant fluid from mast cells which had been incubated with C48/80 elsewhere. Control sections were kept in the medium alone. Examination by electron microscopy showed that exposure of brain sections to activated mast cells in the presence of other peritoneal cells resulted in the destruction of myelin and some neuronal degeneration. Mast cells, along with macrophages, may be involved in demyelinative or inflammatory diseases of the nervous system, such as multiple sclerosis (MS).