IL-2 signaling was required for optimal IL-9 expression in ex vivo cultures of PBMCs from patients with smoldering/chronic ATL. (A) IL-2, IL-9, and Tax mRNA levels were determined every day in ex vivo cultures by TaqMan real-time RT-PCR. The copy numbers of IL-2, IL-9, and Tax mRNA were normalized to the copy number of hypoxanthine guanine phosphoribosyl transferase 1 (HPRT1) mRNA. The data are representative of data from 4 different patients. (B) IL-2, IL-9, and Tax mRNA levels in the presence of 10 μg/mL anti–IL-2R-α every day in ex vivo cultures by TaqMan real-time RT-PCR. The data are representative of data from 2 different patients.