CD4 and tropical spastic paraparesis: The human T cell leukemia/lymphotropic virus type 1 is the etiologic agent of adult T cell leukemia (ATL), an aggressive and fatal leukemia of CD4+ T lymphocytes [1,2] and is also associated with a neurological demyelinating disease, tropical spastic paraparesis (TSP) or HTLV-I associated myelopathy (HAM)[3].