IFNG and tropical spastic paraparesis: Furthermore, patients with HAM/TSP also present withhigh numbers of HTLV-1 Tax-specific CD8+ T cells in the cerebrospinal fluid[15], [19], [20], [21], [22] that arethought to play a immunopathogenic role, either by release of neurotoxic cytokines,such as TNF-α and IFN-γ [23], [24], or by direct cytotoxicity.