To investigate whether CCL1 expression is associated with the in vivo pathogenesis of HAM/TSP, we performed ELISAs to measure the plasma levels of CCL1 in 31 patients with HAM/TSP, 13 HTLV-1-seronegative patients with MS, 19 HCs, and 10 NCs (Fig. 5). This evidence concerns the gene CCL1 and tropical spastic paraparesis.