TNF and tropical spastic paraparesis: Although increased TNF-α and IL-6 levels were not evident in the CSF in our study population, reduced TGF-β1 in HTLV-1-infected individuals might be related to chronic inflammatory stimulation in the CNS by infected cells, which are present in the CSF of both HTLV-1 AC and HAM/TSP patients, as previously shown [11].