FIGURE 5

Brain-infiltrating BG1 CD8⁺ T cells enter into the CNS of young mice and have memory-like phenotypes with limited inflammatory and cytotoxic function. (A–C) Absolute numbers of lymphocytes in the brain and (D–F) spinal cord were determined for three different age groups. CD8 T cells (Thy1.2⁺ CD8⁺ CD4^- B220^-), CD4 T cells (Thy1.2⁺ CD8^- CD4⁺ B220^-) and B cells (Thy1.2^- CD8^- CD4^- B220⁺) were identified by flow cytometry. (G) BG1 CD8 T cell subsets within the brain were determined by the expression of CD62L, CD44, CD127, KLRG1, CD103 and CD69 as shown in Fig. S2. CD8 T cells were defined as T_CM (CD62L⁺ CD44⁺ KLRG1^-), T_EM (CD62L^- CD44⁺ KLRG1^-) and T_EFF (CD62L- CD44+ KLRG1+) or TRM (CD44+ CD69⁺ CD103⁺). (H) BG1 CD8 T cells within the brain of 45–60 day old BG1 mice poorly secrete IFNγ and IL-17A, and (I) lack granzyme B production. Data shown are from at least six individual mice per group. Error bars in graphs represent SEM. *; P=<0.05, **; P=<0.01, ***; P=<0.001, ^ns; Not Significant.