Increased expression of IL-15Rα in the PBMCs from patients with T-LGL leukemia. (A) TaqMan real-time RT-PCR analysis of IL-15Rα mRNA levels in the PBMCs from patients with T-LGL leukemia. The copy numbers of IL-15Rα mRNA were normalized to the copy number of HPRT1 mRNA. The fold induction was calculated based on the normalized IL-15Rα mRNA copy number in PBMCs from normal donors (n = 3). (B) FACS analysis of the cell surface expression of IL-15Rα on both CD8⁺ T cells and monocytes in PBMCs from T-LGL leukemic patients compared with those from normal donors. The data from patient LGL1 are representative of those from 2 T-LGL patients who showed IL-15Rα expression on both CD8⁺ cells and monocytes. The data from patient LGL3 are representative of those from patients that showed IL-15Rα expression on monocytes alone. CD14 was used as the monocyte marker.