5-HT induces cell death in group 1 BL cells.

L3055 cells cultured at an initial density of 10⁵/mL were treated with 1 to 150 μM of 5-HT for 24 hours, as indicated. At the end of the incubation, cells were analyzed as follows. (A) By forward (FS) versus side scatter (SS) analysis and gated into 2 different populations: viable (relatively high FS and low SS) cells (black dots) and dead (relatively low FS and high SS) cells (red dots). Percentage viable cells are indicated for each treatment. (B) By FACS analysis of styo 16–PI double-stained cells: syto 16^+ve/PI^−ve (viable) cells shown in upper left quadrant in green, syto 16^−ve/PI^−ve shown in lower left quadrant in blue, syto 16^−ve/PI^+veshown in lower right quadrant in red. Cells used in panel A were approximately at passage 40, whereas those for panel B were approximately at passage 35. All results shown are representative of 3 similar experiments.