Human T lymphotropic virus type 1 (HTLV-1) -associated myelopathy/tropic spastic paraparesis is a demyelinating inflammatory neurologic disease associated with HTLV-1 infection. HTLV-1 Tax11–19-specific cytotoxic T cells have been isolated from HLA-A2-positive patients. We have used a peptide-loaded soluble HLA-A2–Ig complex to directly visualize HTLV-1 Tax11–19-specific T cells from peripheral blood and cerebrospinal fluid withoutin vitrostimulation. Five of six HTLV-1-associated myelopathy/tropic spastic paraparesis patients carried a significant number (up to 13.87%) of CD8⁺lymphocytes specific for the HTLV-1 Tax11–19 peptide in their peripheral blood, which were not found in healthy controls. Simultaneous comparison of peripheral blood and cerebrospinal fluid from one patient revealed 2.5-fold more Tax11–19-specific T cells in the cerebrospinal fluid (23.7% vs. 9.4% in peripheral blood lymphocyte). Tax11–19-specific T cells were seen consistently over a 9-yr time course in one patient as far as 19 yrs after the onset of clinical symptoms. Further analysis of HTLV-1 Tax11–19-specific CD8⁺T lymphocytes in HAM/TSP patients showed different expression patterns of activation markers, intracellular TNF-α and γ-interferon depending on the severity of the disease. Thus, visualization of antigen-specific T cells demonstrates that HTLV-1 Tax11–19-specific CD8⁺T cells are activated, persist during the chronic phase of the disease, and accumulate in cerebrospinal fluid, showing their pivotal role in the pathogenesis of this neurologic disease.

5-Lipoxygenase (5-LO) is the key enzyme in the biosynthesis of proinflammatory leukotrienes. This study showed that various forms of cell stress, such as chemical stress (sodium arsenite), osmotic stress, or heat shock lead to substantial formation of 5-LO products in freshly isolated human polymorphonuclear leukocytes (PMNLs), when exogenous arachidonic acid (10 μM) was present. In parallel, cell stress led to activation of p38 MAPK (mitogen-activated protein kinase) and mitogen-activated protein kinase-activated protein kinases (MAPKAPKs) kinases, which can phosphorylate 5-LO in vitro. Interestingly, arsenite also caused redistribution of 5-LO from the cytosol to the nuclear membrane. Only minor activation of extracellular signal-regulated kinases and c-jun NH₂-terminal kinases was observed, implying that these MAPKs are less important for 5-LO product formation in stress-stimulated PMNLs. Stimulation of 5-LO product formation by Ca⁺⁺-ionophore A23187 or thapsigargin depended on Ca⁺⁺; almost no 5-LO product formation was observed in freshly isolated PMNLs when Ca⁺⁺ was depleted by chelating agents. Also the response toN-formylmethionyl-leucyl-phenylalanine (fMLP) was clearly diminished, but some 5-LO product formation remained. In contrast, stress-induced product formation and translocation of 5-LO, as well as activation of p38 MAPK, occurred also after Ca⁺⁺ depletion. Moreover, the p38 MAPK inhibitor SB203580 blocked stress-induced 5-LO product formation efficiently, whereas ionophore- or thapsigargin-induced formation of 5-LO products was less sensitive. These data show that cell stress can activate 5-LO in isolated PMNLs by a mechanism that does not involve Ca⁺⁺ mobilization. This mechanism could function independently of Ca⁺⁺-mediated 5-LO activation for stimulation of leukotriene biosynthesis under physiologic conditions as well as in inflammatory diseases.

To discern the T cell subtype associated with T cell differentiation, the expression of CD45RA and CD27 was measured from total CD8high cells and fro

Human T cell leukemia virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive neurologic disease characterized by marked degeneration of the spinal cord and the presence of infiltrating CD8+ T cells and macrophages. HAM/TSP patients have very high frequencies of HTLV-I-specific CD8+ CTL in peripheral blood and in cerebrospinal fluid. In this study, we show that HAM/TSP patients also have elevated levels of peripheral blood CD8+ T cells that produce intracellular IFN-gamma. To address the potential role of soluble mediators secreted by CD8+ T cells in the pathogenesis of HAM/TSP, we have analyzed the capacity of a panel of nine HTLV-I-specific CD8+ CTL clones derived from three HAM/TSP patients to secrete cytokines, chemokines, and matrix metalloproteinases. The results demonstrate that the majority of these CTL clones secrete IFN-gamma, TNF-alpha, macrophage-inflammatory protein-1alpha and -1beta, IL-16, and matrix metalloproteinase-9. These findings indicate that HTLV-I-specific CD8+ CTL are an important source of proinflammatory soluble mediators that may contribute significantly to the pathogenesis of HAM/TSP.