We have previously shown that patients with HAM/TSP display a decreased ability to down-modulate T cell response (Santos et al. 2006) in comparison with HTLV-1 carriers and that CD8 T cells are the main source of IFN-γ and TNF among T cells in HAM/TSP (Santos et al. 2004). The gene discussed is CD8A; the disease is tropical spastic paraparesis.