IL6 and tropical spastic paraparesis: To that end, the concentrations of VILIP-1, BDNF, VEGF, β-NGF, TGF-β1, fractalkine/CX3CL1, IL-6, IL-18, and TNF-α, and the soluble forms of TREM-1, TREM-2, and RAGE, were assessed using a multiplex bead-based immunoassay in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n = 20), asymptomatic HTLV-1 carriers (AC) (n = 13), and HTLV-1-seronegative individuals (n = 9), with the results analyzed according to the speed of HAM/TSP progression.