CD30 Activation Induced Eosinophil Apoptosis is Mediated by Caspase-9 / 소아알레르기및호흡기학회지

ABSTRACT

PURPOSE: Although CD30 is known to be expressed more on eosinophils undergoing apoptosis, it is still not known how CD30 activation leads to eosinophil apoptosis. In this study, we evaluated whether ligation of CD30 incites apoptosis and investigated whether the mechanisms of CD30 induced eosinophil apoptosis are dependent on caspase activation. METHODS: We drew 90 mL of peripheral blood from healthy donors and then purified eosinophils using a MACS system. Expression of CD30 on eosinophils was measured, and eosinophils were cultured in wells pretreated with anti-CD30 mAb, isotype control immunoglobulin G1, interleukin (IL)-5, and dexamethasone in Roswell Park Memorial Institute 1640 media supplemented with 10% fetal bovine serum. Their rates of apoptosis were then compared using flow cytometry. To evaluate whether caspase-9 is involved in CD30-induced eosinophil apoptosis, the apoptotic rate was evaluated after the addition of caspase-9 inhibitor. The expression of procaspase-9 was also measured using Western blot. RESULTS: Expression of CD30 molecules on eosinophils increased steadily as the culture time lapse. The apoptotic rates of eosinophils cultured in the presence of anti-CD30 mAb were significantly increased to 29.1+/-6.1% and 47.3+/-4.7% compared to 17.1+/-6.7% and 29.4+/-9.2% of the control at 4 and 24 hours, respectively (both P<0.05). The apoptotic rates of eosinophils treated with anti-CD30 mAb were even faster than those of eosinophils treated with dexamethasone, and the mAb also suppressed the IL-5-induced enhancing effect of eosinophil survival. Caspase-9 inhibitor suppressed mAb induced eosinophil apoptosis from 54.8+/-6.9% and 71.5+/-11.6% to 24.5+/-6.0% and 47.8+/-11.4% at 18 and 36 hours, respectively (both P<0.001). We also demonstrated that the expression of procaspase-9 with mAb was diminished compared to that of the control and of IL-5. CONCLUSION: This study showed CD30 activation enhances eosinophil apoptosis, and the effect is mediated by caspase-9 activation.