The effect of HeFi-1 and daclizumab on the proliferation and cell cycle of karpas299 cells in vitro. (A) Karpas299 cells were incubated with medium alone or with antibodies (20 μg/mL) at 37°C for 42 hours and pulsed with 1 μCi (0.037 MBq) [³H]thymidine for 6 hours. The cells then were harvested and counted. The data represent mean ± SD of triplicates and are representative of 3 experiments. HeFi-1 inhibited the proliferation of karpas299 cells, whereas daclizumab did not inhibit the proliferation. CPM indicates counts per minute. (B) The cells were harvested for flow cytometric analysis after incubating with medium alone or with antibodies (20 μg/mL) for 48 hours. Percentage of apoptotic cells with sub-G1 DNA content (M1 phase) was indicated in the histograms, and the percentages of cells in different phases of the cell cycle were analyzed using Modfit software. Similar results were obtained in 3 independent experiments. HeFi-1 caused cell-cycle arrest as defined by the reduced percentage of the cells in S phase and the increased percentage in G1 phase when compared with those of the cells treated with medium alone or B3 antibody. The daclizumab did not show induction of apoptosis or cell-cycle arrest.