Cytokines up-regulate Ia expression in organotypic cultures of central nervous system tissue.

Myelinated cultures of embryonic SJL/J mouse spinal cord tissue have been tested for their ability to express class II major histocompatibility complex (MHC) (Ia) molecules in the presence of two recombinant cytokines, mouse interferon-gamma (IFN-gamma) and human tumor necrosis factor-alpha (TNF-alpha). Both cytokines up-regulated class II MHC in a dose-dependent manner and interacted synergistically to increase Ia when applied together. The principal cell type involved were glial fibrillary acidic protein-positive astrocytes along the surface of the cultures. Immunocytochemistry in combination with light microscope examination of whole mounts and epoxy sections as well as electron microscopy, were used to assess the phenomena. These findings add further weight to previous observations on astrocytes being capable of serving as antigen-presenting cells within the central nervous system.