Human T cell leukemia virus type I (HTLV-I) infection induces greater expansions of CD8 T lymphocytes in persons with HTLV-I-associated myelopathy/tropical spastic paraparesis than in asymptomatic carriers

A quantitative study of the T cell receptor repertoire was performed ex viv o on CD4 and CD8 T cell subsets of human T cell leukemia virus type I (HTLV -I)-infected asymptomatic carriers and patients with HTLV-I-associated myel opathy/tropical spastic paraparesis (HAM/TSP). Indexes of oligoclonality th at compiled all repertoire modifications were calculated for peripheral blo od mononuclear cells and for CD4 and CD8 T cell subsets. Both patients with HAM/TSP and asymptomatic carriers had greater T lymphocyte expansions than did uninfected donors, which was independent of age and at least twice hig her in the CD8 than in the CD4 cell compartment. Some expanded CD8 T cells corresponded to cytotoxic T lymphocytes directed against various epitopes o f the immunodominant Tax protein. Patients with HAM/TSP had significantly h igher CD8 cell expansions than did asymptomatic carriers. These results hig hlight the prognostic value of measuring CD8 T cell expansions during follo w-up of HTLV-I infection.