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

-susceptible Rat Strains. We examined 11,6 production by Lewis and BN astrocytes in response to LPS, IFN-y, and IL11B to determine ifdifferential cytokine expression by these cells extended to 1176 . We have recently demonstrated that primary rat astrocytes secrete IL6 upon stimulation with LPS or the cytokines TNF-a and IL1a. IFN-y alone has no effect on IL-6 production, but synergizes with 11710 for enhanced IIr6 expression (14) . Lewis and BN astrocytes were treated with LPS (1 P.g/ml) with or without IFN -'y (100 U/ml), IFN-y (100 U/ml), and ILl)3 (1,000 U/ml), or with IFN-y (100 U/ml) plus IL1O (1,000 U/ml) for 18 h, at which point the supernatants were harvested and assayed for IL6 production . Both Lewis and BN astrocytes secrete low levels of IL6 protein in response to LPS alone, and IFN-y synergizes with LPS to enhance 11,6 secretion . IFN-y alone does not induce IL-6 production, but enhances IIAO-induced IL6 expression (Table 3) . These findings demonstrate that Lewis and BN astrocytes make comparable amounts of IL6 protein in response to LPS, IFN-y/LPS,11,10, and IFN-y/IL10, and indicate that differences in TNF-ca production appear to be selective.