The number of BTLA-expressing B cells and CD19+/BTLA+/IL-10+ cells obviously decreased in multiple sclerosis (MS) cases, while the remission of fingolimod-induced relapsed-remitted MS is related to a significantly increased number of CD19+/BTLA+/IL-10+ B lymphocytes (80). The gene discussed is BTLA; the disease is myeloid sarcoma.