IL-2–dependent ATL cells and HTLV-1–transformed cell lines are resistant to the TGF-β1–induced growth inhibition.

(A) PBMCs, MT2 and HUT102 cell lines, and IL-2–dependent fresh ATL cells from patients (Champ, Sted, Pabe) were stimulated with PHA (1 μg/mL) and IL-2 (10 IU/mL) in the presence or in the absence of TGF-β1 (2 ng/mL) for 72 hours, and their proliferation was determined as described in “Materials and methods.” The results are representative of 3 independent experiments, each conducted in triplicate. (B) PBMCs and ΔU3CMVGFP- or ΔU3CMVTax-transduced PBMCs were stimulated with either PHA/IL-2 (i) or anti-CD3 (100 ng/mL; ii) in the presence or in the absence of TGF-β1 (2 ng/mL) for 72 hours and their proliferation was determined as described in “Materials and methods.” The results are representative of 3 independent experiments, each conducted in triplicate. Tax expression in ΔU3CMVTax-transduced PBMCs, as compared with ΔU3CMVGFP or untransduced PBMCs, is detected with an anti-Tax antibody by immunoblot assay (iii) or immunofluorescence (iv). Original magnification Biv, × 40.