IL-7 and IL-15 prolong the survival of patient Sézary cells in vitro. The IL concentrations are the same as in Fig 1. The cells of patient 1 (A) were kept at these concentrations for the whole time of the experiment. The transient increase of the number of cells from patient 2 (B) on day 13 is caused by an increase of the concentrations of IL-7 and IL-15 to 20 ng/mL and 40 ng/mL, respectively. The data were obtained from three independent experiments.