Phenotypic characterization of B-CLL cells after 3 days of stimulation by CD40L or mock-transfected NIH3T3 fibroblasts in the presence of IL-2 (20 IU/mL), IL-4 (1 IU/mL), and IFNγ (20 IU/mL). Blank areas represent the isotype-matched control antibodies and the solid areas represent the fluorescence distribution of the MoAbs tested as assessed by flow cytometric analysis. The results shown are from one experiment and are representative of three independent experiments.