Figure 4. Peripheral and CnS activation of myelin-specific CD8+ T cells.
CD8+ T cells are primed by cross-presentation by dendritic cells (DCs) in the lymph nodes (1) and follow the same steps (2–5) as CD4+ T cells (see FIG. 2). However, CD8+ T cells are activated by macrophages, microglial cells and DCs only by cross-presentation; endothelial cells can directly present antigen if they have access to myelin epitopes (6). Activated macrophages, microglial cells and CD8+ T cells secrete soluble mediators, and CD8+ T cells can directly lyse oligodendrocytes expressing MHC class I and myelin epitopes (7). CSF, cerebrospinal fluid; TCR, T cell receptor; TReg, regulator T.