Flow cytometric analysis of apoptosis in SMS-SB cells. Cultures of SMS-SB cells in PFHMII were established as described in the legend to Fig 2. After 24 hours of culture, the cells were harvested, stained simultaneously with propidium iodide and Hoechst 33342, and after gating on forward and side scatter parameters, analyzed by two-laser cytometry.35 (A) And (B), respectively, present the data for SMS-SB cells obtained from normal and low cell density cultures, and (C) and (D) illustrate the effect of either 100 ng/mL sCD23 or 20 U/mL IL-4, respectively, on the extent of apoptosis in the cultures. On the individual panels, the percentage figures shown on the lower left quadrant represent viable cells and those on the lower right represent dead cells. Values in the upper left quadrant refer to early apoptotic cells while those in the upper right represent late apoptotic cells. The experiment shown is representative of four independent repeats.
