Direct analysis of viral-specific CD8(+) T cells with soluble HLA-A2/Tax11-19 tetramer complexes in patients with human T cell lymphotropic virus-associated myelopathy

Human T cell lymphotropic virus-I (HTLV-I)-associated myelopathy is a slowl y progressive neurologic disease characterized by inflammatory infiltrates in the central nervous system accompanied by clonal expansion of HTLV-I-rea ctive CD8(+) T-cells, In patients carrying the HLA-A2 allele, the immune re sponse is primarily directed to the Tax11-19 peptide. The frequency, activa tion state, and TCR usage of HLA-A2/Tax11-19 binding T cells in patients wi th HTLV-I-associated myelopathy was determined using MHC class I tetramers loaded with the Tax11-19 peptide. Circulating Tax11-19-reactive T cells wer e found at very high frequencies, approaching 1:10 circulating CD8(+) T cel ls. T cells binding HLA-A2/Tax11-19 consisted of heterogeneous populations expressing different chemokine receptors and the IL-2R beta-chain but not t he IL-2R alpha-chain, Additionally, Tax11-19-reactive CD8+ T cells used one predominant TCR V beta-chain for the recognition of the HLA-A2/Tax11-19 co mplex. These data provide direct evidence for high frequencies of circulati ng Tax11-19-reactive CD8(+) T cells in patients with HTLV-1-associated myel opathy.