Comparison and quantitation of Ia antigen expression on cultured macroglia and ameboid microglia from Lewis rat cerebral cortex: analyses and implications.

We isolated two subclasses of astrocytes, oligodendrocytes and ameboid microglia from Lewis rat cerebral cortex and analyzed Ia antigen expression on each glial cell type by immunofluorescent microscopy and cytofluorometry. All of these expressed little or no Ia without interferon-gamma (IFN-gamma) treatment. Following IFN-gamma treatment, Ia expression was observed on a majority (approximately 80%) of ameboid microglia, on half (approximately 55%) of the type 1 astrocytes, on a small number (approximately 7%) of type 2 astrocytes, but not on oligodendrocytes. These findings suggest that the type 1 astrocyte and microglia may play more predominant roles in Ia-related, immune-mediated intracerebral lesions although the type 2 astrocytes may also be involved.