Differential tumor necrosis factor alpha expression by astrocytes from experimental allergic encephalomyelitis-susceptible and -resistant rat strains

As mentioned previously, EAE is characterized by the infiltration of mononuclear cells into the CNS, with the predominant cell types being activated T cells and macrophages. Activated T cells in the Lewis CNS could serve as an endogenous source of the rytokine IFN-y, and prime astrocytes for TNF-a expression . Infiltrating macrophages and resident astrocytes/microglia represent sources of ILI that could interact with IFN-y-primed astrocytes, resulting in TNF-a production . TNF-a production by Lewis astrocytes in response to IFN-y and IIJ1 may perpetuate the influx of non-antigenspecific inflammatory cells into the CNS by increasing the permeability of endothelial cells (48) , and by enhancing expression of adhesion molecules on both brain endothelium and astrocytes (19, 49) . Additionally, astrocyte TNF-a production may kill or damage neighboring oligodendrocytes (12) and directly damage the myelin sheath (21) , contributing to demyelination .