Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is an inflammatory disease of the central nervous system (CNS); however, the mechanism by which HTLV-1 induces HAM/TSP is not yet clear. The virus–host interaction may provoke changes in the immunological response, such as the enhanced production of inflammatory cytokines, which are implicated in the pathogenesis of HAM/TSP. This work aimed to analyze the peripheral immune response of patients infected with HTLV-1 and correlate it with functional neurological manifestations in patients with HAM/TSP. In the current study, 69 HTLV-1 infected patients were studied. 26 of them developed HAM/TSP and 43 didn’t develop HAM/TSP. In patients with HAM/TSP was evaluated the functional neurological manifestations like muscle strength, muscle tone, balance and walking aid. Five mL peripheral blood was collected into a tube with EDTA and lymphomononuclear cells were separated on a Ficoll-PaqueTM Plus density gradient (GE Healthcare). Total RNA was extracted from 106 cells with Trizol reagent. After RNA quantification, 1 μg of total RNA was submitted to reverse transcription for the generation of cDNA using the Superscript III kit (Invitrogen). IFN-, TNF-, IL-4, IL-10 and TGF- gene expression was measured quantitatively with the StepOnePlus Real-Time PCR System (Applied Biosystem) using SYBR Green reagent (Applied Biosystem). The amount of mRNA in the sample was expressed as the relative amount to the GAPDH and β-actin genes, according to the formula 2-Ct, where Ct is Ctgene – Cthousekeeping gene. The gene expression showed higher expression of Th1 cytokine in patients with and without HAM/TSP, principally IFN-. In HAM/TSP patients also showed higher TNF- expression. The gene expression showed lower expression of Th2 cytokine in patients with HAM/TSP. As regards the anti-inflammatory response, gene expression of IL-10 showed impaired in patients with HAM/TSP and expression of TGF- initially showed higher in both groups. After ratio analysis between TGF-andIL it was observed that the expression of TGF-wasequivalent to the expression of IL-10, suggesting its involvement as a non-inflammatory cytokine, but as possible repair action tissue. The inflammatory profile was positively associated with the walking aid and balance, showing significant results only for the expression of IFN-. The patients infected with HTLV-1 who developed HAM/TSP showed increased Th1 response compared to patients who did not develop HAM/TSP, and this increased expression of IFN- is related to the development and progression of the disease.
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