Increased Fas-mediated cytotoxicity of CD4-positive T cells in patients with human T-lymphotropic virus type I-associated myelopathy

Using a

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release assay, we investigated Fas-mediated cytotoxicity of peripheral blood CD4⁺ T cells of patients with human T-lymphotropic virus type-I (HTLV-I)-associated myelopathy (HAM) against T98G, a glioblastoma cell line which expresses Fas. Cytotoxic activity of CD4⁺ T cells against T98G was significantly higher in HAM patients than in controls. Moreover, when CD4⁺ T cells of HAM patients were preincubated with a monoclonal antibody to human Fas ligand (FasL), cytotoxic activity against T98G was significantly suppressed. These results suggest that damage to nervous tissues by the Fas/FasL system is involved in the pathogenesis of HAM.