IA EXPRESSION AND ANTIGEN PRESENTATION BY GLIA - STRAIN AND CELL-TYPE-SPECIFIC DIFFERENCES AMONG RAT ASTROCYTES AND MICROGLIA

Astrocytes from experimental allergic encephalomyelitis (EAE)-suscepti ble Lewis rats expressed higher levels of Interferon-gamma-inducible I a than astrocytes from EAE-resistant Brown Norway (BN) rats, whereas B N microglia expressed higher Ia than Lewis at both mRNA and protein le vels. Lewis astrocytes induced proliferation of MBP-specific T cells s elected on Lewis background as efficiently as Lewis thymocytes, wherea s BN astrocytes were much less efficient in stimulating T cells select ed in the presence of BN thymocytes. Microglia, irrespective of strain , induced only weak proliferative responses of these T cells despite t he high expression of Ia. Antigen-stimulated T cells underwent apoptos is in the presence of microglia but not astrocytes. Thus, astrocyte-me diated proliferation of MBP-specific T cells may contribute to the dev elopment of EAE, while microglia-induced T cell apoptosis may downregu late immunopathological processes in the brain. (C) 1997 Elsevier Scie nce B.V.