Spontaneous degranulation and IFN-γ production in CD8⁺ T cells of HAM/TSP patients. (A) Flow cytometric analysis of CD107a/IFN-γ expression in CD8⁺ T cells of an ND and a representative HAM/TSP patient (HAM#1) after culture for 5 and 24 hours. Cells were cultured in the absence of any additional stimulators. (B) Time course of CD107a/IFN-γ expression in CD8⁺ T cells of NDs (ND#1-3) and HTLV-I–infected patients (AC#1-3 and HAM#1-3). PBMCs were cultured for 5 to 48 hours, and analyzed by flow cytometry at each time point. (C) Comparison of CD107a/IFN-γ expression in CD8⁺ T cells of HTLV-I–infected patients at 24 hours culture. The data were obtained from 5 ACs and 9 patients with HAM/TSP. The horizontal line represents the median, the box represents the 25th percentile, and the whiskers represent the 75th percentile. (D) Time course of Tax mRNA expression in NDs (ND#1-3) and HTLV-I–infected patients (AC#1-3 and HAM#1-3). This experiment was performed at the same time points as with Figure 1B, and total RNAs were isolated from cultured cells at each time point.