TheIL-18,IL-12, andIFN-gamma expression in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients, HTLV-1 carriers, and healthy subjects

Interleukin (IL)-12, IL-18, and interferon gamma (IFN-gamma) can induce Th1-inflammatory responses in favor of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) manifestation. In this study, the gene expression and plasma levels of these cytokines were evaluated. The peripheral blood mononuclear cells (PBMCs) in 20 HAM/TSP patients, 21 asymptomatic carriers (ACs), and 21 healthy subjects (HSs) were assessed for the expression ofIL-18,IL-12, andIFN-gamma, using qRT-PCR. The plasma level of IL-18 and IFN-gamma were measured by an ELISA method. The mean of HTLV-1 proviral load (PVL) in the HAM/TSPs was 1846.59 +/- 273.25 and higher than ACs at 719.58 +/- 150.72 (p = 0.001). TheIL-12was considerably expressed only in nine ACs, five HAM/TSPs, and all HSs. Furthermore, the gene expression and plasma levels of IL-18 were lower in the HTLV-1-positive group than the control group (p = 0.001 and 0.012, respectively); however, there was no significant difference between the ACs and HAM/TSPs. TheIFN-gamma level was higher in the HTLV-1-positive group (p < 0.001) than HSs. Although there were no correlation between plasma levels of IL-18 and IFN-gamma with PVL in the ACs, a positive correlation was observed between plasma IL-18 levels and PVL (r = 0.654,p = 0.002). The highest levels ofIFN-gamma were observed in the HAM/TSPs which has a significant correlation with HTLV-1-HBZ(r = 0.387,p = 0.05) but not withTax. However, no significant correlation was found between PVL and proinflammatory pattern. Apart from the IFN-gamma as a lymphokine, as a host factor, and HTLV-1-HBZ, as a viral agent, the other proinflammatory monokines or HTLV-1 factors are among the less-effective agents in the maintenance of HAM/TSP.