Figure 2: Percentage of T cells in the brain of controls and SIV-infected rhesus macaques exhibiting REG or RAP disease course. Brain cell suspensions were stained with fluorescent-labelled antibodies against CD3, CD4, and CD8 surface markers to identify CD3+CD4+ T helper cells and CD3+CD8+ cytotoxic T cells, using flow cytometry. in comparison to uninfected control animals.