Expression of MHC class I and β2-microglobulin in rat spinal motoneurons:: Regulatory influences by IFN-gamma and axotomy

The low expression of MHC antigens is believed to be one factor of importance contributing to the immune-priveleged status of CNS neurons. We here describe that motoneurons, in contrast; to other nerve cells in the lumbar spinal cord of the adult rat, express both MHC class I and beta 2-microglobulin mRNA, The motoneurons also display in situ hybridization signal for IFN-gamma receptor mRNA, After a peripheral axotomy, the motoneurons show a clear upregulation of beta 2-microglobulin mRNA. IFN-gamma treatment of cultured rat embryonic spinal motoneurons causes a similar upregulation of especially beta 2-microglobulin. Based on these facts, we propose that spinal motoneurons can be influenced by IFN-gamma and recognized by cytotoxic CD8+ T-cells. These findings could be of relevance in the search for pathogenetic mechanisms in motoneuron-specific diseases, such as ALS. (C) 1998 Academic Press.