Resistance of Th17 cells to AICD is due to abundant c-FLIP expression. (A) c-FLIPL and Bcl-xL protein expression was detected with Western blot. Th1 and Th17 cells were treated with 0, 1, or 10 μg/mL anti-CD3 mAb. β-Actin was used as a loading control. Data represent 1 of 3 replicate experiments. (B) Expression levels of c-FLIPL, Bcl-xL, and β-actin in Th17 cells shown after control, c-FLIP, or Bcl-xL siRNA transfection. (C) AICD of Th17 cells after knocking down c-FLIP or Bcl-xL. Polarized Th17 cells transfected with control, c-FLIP–specific, or Bcl-xL–specific siRNA for 48 hours were recultured with medium, anti-CD3 mAb alone, or anti-CD3 plus neutralizing anti-FasL mAb. Apoptosis was determined 20 hours after restimulation by annexin V and DAPI staining. Data represent 1 of 3 replicate experiments.
