Participation of poly(ADP-ribose) synthetase in the process of norepinephrine-induced inhibition of major histocompatibility complex class II antigen expression in human astrocytoma cells.

We previously demonstrated that the expression of a transfected poly(ADP-ribose) synthetase cDNA into macrophage tumor cells inhibited interferon-gamma-dependent induction of major histocompatibility complex(MHC) class II antigens. In the present study, we found that addition of norepinephrine to the cultured human astrocytoma STTG1 cells induced mRNA of poly(ADP-ribose) synthetase in 6-14h. Thus, we cultured the cells in the presence of norepinephrine for 24h, and then induced the MHC class II antigen by the addition of interferon-gamma. The expression of MHC class II antigen was inhibited, whereas it was not inhibited when norepinephrine and interferon-gamma were simultaneously added into the culture medium. These results suggest that an increase of poly(ADP-ribose) synthetase by norepinephrine cause the inhibition of interferon-gamma-mediated MHC class II antigen expression.