CD8+ T cells ubiquitously express the major histocompatibility complex class I (MHC-I), which intriguingly is also expressed in the oligodendrocytes, astrocytes, and neurons of MS patients, suggesting that these antigen-presenting glial cells may increase the frequency of pathogenic CD8+ T cells through antigen presentation to reactive T cells in the brain parenchyma [30]. The gene discussed is CD8A; the disease is myeloid sarcoma.