Figure 2

IFN-α suppressed Tax protein expression before an apparent reduction in HTLV-1 mRNA levels. A. The effects of IFN-α (3000 IU/ml) on intracellular Tax (top) and Gag (bottom) protein expression in ILT-Hod (left) and ILT-#29 (right) cells was evaluated by flow cytometry on days 1, 3, and 8 of culture. Cells stained with isotype antibodies served as negative controls. The values inside the dot plots represent percentages of viral protein-expressing cells, and the relative values in IFN-α-treated (closed bar) against untreated (open bar) samples are shown in the bar graph. The MFI value of the total cell population is indicated below the dot plots. B. Expression of HTLV-1 mRNA in the same cell samples prepared in A was evaluated by quantitative RT-PCR using pX (top) and Gag (bottom) primers. Results are standardized and presented as relative values of IFN-α-treated (closed bar) against untreated (open bar) samples. The means and SD of duplicate samples are indicated. *p < 0.05. C. HTLV-1 proteins (Tax and Gag) and HTLV-1 mRNAs expression in ILT-Hod and ILT-#29 cells were measured 24 h after incubation with (closed bar) or without (open bar) IFN-α, and the relative values were indicated as the means and SD of three independent experiments. Three different primer sets (pX, RPX, and Gag) were used to quantify HTLV-1 mRNAs. D. Seven ILT lines from various patients and HUT102 were cultured with or without IFN-α for 24 h, and the proportions of Tax positive cells (left) and the HTLV-1 mRNA quantified using pX (middle) and RPX (right) primers were indicated as relative values against the sample without IFN-α. E. Various HTLV-1-infected T cell lines shown in D were cultured with or without IFN-α for 3–4 days, and viable cell numbers analyzed by a colorimetric assay were indicated as relative values.