CXCL10 and tropical spastic paraparesis: Importantly, consistent with the cell line data, the expression levels of CXCL10 mRNA in PBMCs of HAM/TSP patients were also not significantly correlated with the tax expression (p = 0.4247, r = − 0.406 by Spearman rank correlation analysis), indicating that increased CXCL10 expression is independent of tax expression.