Expression of IFN-gamma in cerebrovascular endothelial cells from aged mice

Recently, it has become clear that interferon-gamma (IFN-gamma) plays a rol e in the central nervous system (CNS) as well as in the immune system. Howe ver, the reason for the alteration in IFN-gamma production in the brain wit h aging remains unknown. In this study, we investigated the expression of I FN-gamma in the brain in terms of both mRNA and protein and compared the ex pression in young adult brain with that in aged mice. The cerebrum and cere bellum were collected from young adult (8-10 weeks old) and aged (24-26 mon ths old) BALB/c mice, and the expressions of IFN-gamma and IFN-gamma recept or-1 (IFNGR-1) mRNA were examined by RT-PCR, Expression of IFN-gamma mRNA w as detected in the brains from aged mice but not in those from young adult mice. However, IFNGR-1 mRNA was expressed in the brains from both young adu lt and aged mice. Moreover, IFN-gamma levels in the cerebrum and cerebellum from aged mice were detectable by ELISA, but IFN-gamma was undetectable in these tissues from young adult mice. To identify the cellular source of IF N-gamma in the brain of aged mice, immunostaining using antimouse IFN-gamma monoclonal antibody (mAb) was done. Immunoreactivity of IFN-gamma appeared to be located in cerebrovascular endothelial cells, including the choroid plexus of the cerebellum from aged mice. Expression of IFN-gamma and IFNGR- 1 was also identified in isolated microvessels from brains. These results s uggest that IFN-gamma plays a role in age-associated changes.