As PBMCs from HTLV-1 infected subjects, especially from HAM/TSP patients, produce more proinflammatory mediators such as CXCL9, CXCL10 and TNF than PBMCs from HS [16], [41], we hypothesized that monocytes may play an important role in the inflammatory response and in the pathogenesis of HAM/TSP. The gene discussed is CXCL9; the disease is tropical spastic paraparesis.