In this study, we retrospectively investigated the clinical course and the time course of CSF marker levels (including CXCL10) in 22 HAM/TSP patients (13 patients who received methylprednisolone pulse therapy, five patients who did not receive any steroid therapy, and four patients who discontinued low-dose oral prednisolone therapy). This evidence concerns the gene CXCL10 and tropical spastic paraparesis.