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

In the present study, we have used triple label immunocy-The Journal of Cell Biology, Volume 109, 1989 Figure 7 . Dorsal funiculus of infected spinal cord, 3 WPI, [3H]thymidine injected 2 h before killing. The lower section is a double exposure showing both GFAP in immunofluorescence and silver grains (bright field). The white triangle in the left upper corner shows a 3H-labeled 04+ GFAP+ CNP-cell. The triangle with a short tail in the middle points to an 04 + only 3H-labeled cell and the thin arrow on the right side points to a large 04+ GFAP+ cell without thymidine label. Bar, 10 #m. tochemistry combined with thymidine autoradiography to characterize in vivo the glial cells reacting to a virus-induced demyelinating disease in mice. We identify some of these cells as members of the O-2A lineage based on their reactivity with the 04 antibody which reacts with sulfatide and another putative glycolipid and which labels O-2A progenitors isolated from the adult rodent nervous system (Wolswijk and Noble, 1989) . In our mice, O, antibody stained cells that were also GFAP+ or CNP+, and stained other cells which were negative for both of these differentiation antigens. While such 04 only cells were rarely seen in normal mice, they were readily found throughout the spinal cord of viral inoculated mice at 1 WPI and were dividing. GFAP+ 0 4and GFAP+ 04+ astrocytes were also more prominent throughout the spinal cord at that time. Later on, antigenic changes were mostly associated with the demyelinating lesions: while CNP reactivity disappeared, cells with 04 reactivity increased in the lesions and both putative O-2A progenitors and type 2 astrocytes were found to incorporate tritiated thymidine after a 2-h :pulse. Remyelination followed and CNP staining returned to control levels.