Identification of immunoglobulin-containing cells in the central nervous system of the mouse following infection with the demyelinating strain of Semliki Forest virus.

Cells within the central nervous system were identified as containing immunoglobulin G, A and M using immunocytochemistry in mice previously infected with Semliki Forest virus, a togavirus causing primary immune-mediated demyelination. Cells positive for these immunoglobulins were counted in cerebellar white matter, parenchyma, meninges and choroid plexus/ventricles. No positively staining cells were seen on day 6 after infection although other inflammatory cells were present at this time and virus-specific immunoglobulin was found in serum. Cells positive for IgG appeared in all areas by day 9 and remained dominant in numbers throughout. IgM-secreting cells appeared in small numbers in the parenchyma first on day 9 and subsequently in other areas, their numbers rising to a maximum on day 12 in all areas and falling thereafter. The number of IgA-secreting cells was small. They appeared by PID 12 and continued to rise on successive sampling days. Initially IgG-positive cells were seen in the perivascular cuffs but by day 12 a few had moved away from the cuffs into the adjacent parenchyma. IgG-positive cells were seen both in and away from cuffs within areas of demyelination. IgM and IgA-positive cells tended to follow the distribution of IgG-positive cells, but in fewer numbers.