HDI increased Tax expression in HTLV-1–infected cells. (A) HDI increased the frequency of Tax expression in CD4⁺ cells (cultured as whole PBMCs for 18 hours) in a dose-dependent manner. NaV and NaB concentrations tested were in the millimolar range. TSA concentrations tested were in the nanomolar range. One representative experiment of 6 is shown. (B) HDIs significantly increased the frequency of Tax⁺ CD4⁺ cells in the absence of CD8⁺ cells; * all P < .008 (Wilcoxon signed rank test; 2-tailed). Horizontal bars represent the median frequency of Tax expression.