Mononuclear cells were prepared from the CNS as previously described by Phillips.
(25) on day 7 after i.c. inoculation.
Three to five brains were pooled per sample.
In brief, animals were sacrificed and perfused with 10 ml of PBS, and a single-cell suspension from the brain was obtained by passing cells through a nylon mesh bag (mesh opening, 64 μm).
Percoll (Pharmacia) was added to a final concentration of 30%, and the lysate was centrifuged at 1,300 × g for 30 min at 4°C.
The cell pellet was resuspended, passed through a cell strainer (pore diameter, 70 μm; Becton Dickinson), and washed.
The cells were then layered over 2 ml of Lympholyte-M (Cedarlane Laboratories) and centrifuged at 1,300 × g for 20 min at room temperature.
Cells were removed from the interface, washed once, and counted.