Proliferating skin-derived mast cells require SCF to survive.

After 6 to 8 weeks in culture with rhuSCF (100 ng/mL) in AIM-V medium, cells (95%-99% mast cells) were washed with PBS and placed into culture with (closed circles and square) or without (open circles and square) rhuSCF (100 ng/mL) in AIM-V medium. Cell numbers and viabilities were measured daily for 6 days. (A) Percent viability (circles). Also shown are the annexin V⁺ cells measured on day 2 (squares). (B) Viable cell numbers. Each data point in panels A and B is the mean ± SD for 3 independent experiments, each performed in duplicate. *, P < .05 for a difference compared to the day 0 value using a one-way repeated measures ANOVA and the Dunnet method for multiple comparisons versus a control. #,P < .05 for a difference between the plus and minus rhuSCF values using a paired t test.