FIG. 2.

Suppression of Tax function by tetracycline in immortalized human T cells. Tesi cells were cultivated in the presence or absence of 1 μg of tetracycline (Tet) per ml. (A) Immunoblot analysis demonstrating suppression of Tax protein expression in the presence of tetracycline by using anti-Tax rabbit serum. Lanes: 1, HuT102 cells; 2, Jurkat cells; 3, Tesi cells; 4, Tesi cells with tetracycline. (B) CAT assay demonstrating suppressed Tax activity in immortalized T cells (Tesi cells). The indicated cells were transfected with 10 μg of the reporter plasmid pU3R1-CAT containing the HTLV-1 promoter which can be stimulated by Tax. Lanes: 1, TRI-1 cells; 2, Jurkat cells; 3, Tesi cells without tetracycline; 4, Tesi cells with 1 μg of tetracycline per ml. The experiment was repeated three times with the same result. (C) Reduced IL-2Rα (CD25) surface expression of immortalized T cells in the presence of tetracycline. Immortalized T cells were stained with anti-CD25–fluorescein isothiocyanate and analyzed by flow cytometry.