FOXP3 and tropical spastic paraparesis: In HAM/TSP patients, CD4+ CD25+ CCR4+ Foxp3– T cells which serve as reservoirs for HTLV-1 (Yamano et al., 2009), express low levels of TGF-β and IL-10, while they express high levels of IFN-γ, thus, this pattern of cytokine production may contribute to disease pathogenesis (Yamano et al., 2009; Quaresma et al., 2016).