IL-21 protected myeloma cells from apoptosis.

Annexin V–FITC and propidium iodide binding were measured by flow cytometry in cell lines IH-1, OH-2, and ANBL-6 after incubation for 72 hours with IL-21 (20 ng/mL) or IL-6 (1 ng/mL). Typical dot plots for the cell line IH-1 are shown in the upper panel. Percentages of viable cells, located in the lower left quadrant of dot plots, are shown in the lower panel. A patient sample (patient 5 in Table 1) is included in the lower panel. Data shown are representative of 3 different experiments, and error bars represent ± 1 SD of duplicate data.