An alternative pathway of nitric oxide production by rat astrocytes requires specific antigen and T cell contact.

Abstract In the present study, we observed an alternative pathway in which nitric oxide (NO) production by rat astrocytes requires specific antigen and cell–cell contact. NO production by astrocytes was significantly inhibited by antibodies against CD40L, B7-1 or B7-2. Astrocyte-derived NO inhibited T cell proliferation and induced T cell apoptosis. In contrast, augmented astrocyte proliferation was correlated to the levels of NO production by astrocytes, implicating a role of NO in regulating local immune responses in the central nervous system. These results suggest that T cell-astrocyte interactions may regulate local immune responses via the NO pathway and influence the fate of infiltrating T cells.