Optic-spinal form of multiple sclerosis and immune-mediated myelopathy in Japan

Optic-spinal form of multiple sclerosis (OS-MS) and HTLV-I associated myelo pathy/tropical spastic paraparesis (HAM/TSP) are two immune-mediated myelop athy relatively common in Japan. (1) Transverse myelitis, once seen in 60% of MS, mostly OS-MS, 30 years ago, drastically decreased (5%) recently in J apan. In contrast, frequency of conventional form of MS (C-MS) increased du ring this period of time. But unlike C-MS in white patients, cerebellar hem ispheric lesions are uncommon in Japanese C-MS. These findings emphasize in fluence of changes in exogenous factors on manifestations of MS and distinc t genetic factors related to MS in Japanese and white patients. (2) To clar ify the reason of high HTLV-I proviral load in HAM/TSP, we studied cellular immune surveillance against HTLV-I and found that significant cytotoxic T lymphocyte activity, and suppressed natural killer activity and antibody-de pendent cell-mediated cytotoxicity in the patients. These altered immune su rveillance may be associated with the spread of HTLV-I infection and the pa thogenesis of HAM/TSP.