Proviral load and immune markers associated with human T‐lymphotropic virus type 1 (HTLV‐1)‐associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Peru

Summary Human T‐lymphotropic virus type 1 (HTLV‐1) is the aetiological agent of HTLV‐1‐associated myelopathy/tropical spastic paraparesis (HAM/TSP). The objective of this study is to identify which ex vivo and in vivo markers are associated independently with HAM/TSP in a Peruvian population. Eighty‐one subjects (33 men/48 women) were enrolled: 35 presented with HAM/TSP, 33 were asymptomatic HTLV‐1 carriers (ACs) and 13 were HTLV‐1‐seronegative controls (SCs). Ex vivo markers included T cell proliferation and Th1 [interferon (IFN)‐γ], Th2 [interleukin (IL)‐4, IL‐5], proinflammatory [tumour necrosis factor (TNF)‐α] and anti‐inflammatory (IL‐10) cytokine production in non‐stimulated peripheral blood mononuclear cell (PBMC) cultures. In vivo CD4 + T cell count, markers of Th1 [interferon‐inducible protein (IP)‐10] and Th2 (sCD30) activity in plasma and HTLV‐1 proviral load in PBMCs were also evaluated. In univariate analysis, several markers, including T cell proliferation, IFN‐γ, IP‐10, sCD30 and proviral load were associated with HAM/TSP, but in a multiple logistic regression analysis only the proviral load remained associated significantly with disease manifestation [adjusted OR 9·10 (1·24–66·91)]. Our findings suggest that HAM/TSP is associated primarily with proviral load, whereas the observed association with some immune markers seems secondary.