Flow cytometry evaluation of the T-cell receptor Vβ repertoire among human T-cell lymphotropic virus type-1 (HTLV-1) infected individuals: Effect of interferon alpha therapy in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is chronic inflammatory disease of the spinal cord characterized by perivascular lymphocytic cuffing and parenchymal lymphocytic infiltration. In this study using flow cytometry, we have investigated the T-cell receptor (TCR) Vβ repertoire of peripheral blood T lymphocytes in 8 HAM/TSP patients, 10 HTLV-1 infected healthy carriers, and 11 uninfected healthy controls to determine if there is a biased usage of TCR Vβ. We found that TCR Vβ7.2 was under-utilized and Vβ12 was over-utilized in CD4+ T cells of HTLV-1 infected individuals compared with healthy uninfected controls, whereas there were no such differences in CD8+ T cells. Comparison of Vβ repertoire changes before and after interferon-alpha (IFN-α) treatment for HAM/TSP revealed that one out of five patients showed dramatic decrease of specific Vβ in CD8+ T cells. Our results suggest that dominant Vβ subpopulations in CD4+ T cells evolved associated with chronic HTLV-1 infection, and IFN-α treatment for HAM/TSP does not induce a specific pattern of TCR Vβ changes.