Proliferation of Tax-specific CD8⁺ cells in HAM/TSP in vitro.

(A) Tax-specific CD8⁺ cells of HAM-4 were identified and quantified, using an HLA-A*0201/Tax tetramer. Dot plots gated on the large cell population (R2) are presented. Percentage of HTLV-I Tax-specific CD8⁺ cells was increased in culture, as indicated in the upper-right quadrants. The number indicates the percentage of Tax-specific CD8⁺ cells in R2 per total CD8⁺ cells in R2. (B) Gating on Tax-specific CD8⁺ cells allowed measurement of proliferation. Numbers indicate the percentage of Tax-specific CD8⁺ cells that incorporated BrdU. These cells showed a very high rate of proliferation in vitro.