IFNG and tropical spastic paraparesis: In this context, HTLV-1-infected CD4 T-cells collected from patients suffering from uveitis, which is the second-most frequent HTLV-1-associated disease in Japan after HAM-TSP, also produce large amounts of various inflammatory cytokines such as IL-1, IL-6, TNF-α, and IFN-γ (98, 99).