In vivo analysis of glial cell phenotypes during a viral demyelinating disease in mice

In the present study, we investigate the possible role of precursor cells in remyelination events using in vivo tritiated thymidine autoradiography combined with immunocytochemistry at regular intervals after viral inoculation. We used three-color immunofluorescence labeling to show simultaneously the 04 antigens, the 2', Y, cyclic-nucleotide 3' phosphohydrolase (CNP) protein (expressed by oligodendrocytes) and the glial fibrillary acidic protein (GFAP) (expressed by astrocytes). The use of the 1-#m frozen section technique (Tokuyasu, 1973 (Tokuyasu, , 1980 Griffith et al., 1984) allows detailed localization of each antigen in different glial cell types (David et al., 1984; Miller et al., 1985) . Using these techniques, we have identified O-2A lineage cells (Raff et al., 1984a) in the spinal cord of normal and diseased mice and followed how these cells are affected by the demyelinating disease. Our results demonstrate that rare 04 precursors present in the normal adult CNS are triggered to divide early in the disease and may give rise to new oligodendrocytes and type 2 astrocytes which both appear instrumental in the reconstruction of myelinated white matter.