CCL1 and tropical spastic paraparesis: We observed that the CCL1 plasma levels were significantly higher in patients with HAM/TSP (mean ± SD: 79.3 ± 30.5 pg/ml) than in HTLV-1-seronegative patients with MS (36.8 ± 11.3 pg/ml), HCs (28.7 ± 2.5 pg/ml), and NCs (28.4 ± 3.2 pg/ml).