In this case, an increase in CD8+ effector T cells (CD45RO−CCR7−) in the cerebrospinal fluid (CSF) was also observed.21 Together with our findings, these suggest that treatment with FTY720 may exacerbate MS symptoms if there is a latent predisposition to, for example, tauopathy, which is hidden by MS symptoms. The gene discussed is CD8A; the disease is myeloid sarcoma.