The CDK inhibitor, R-roscovitine, promotes eosinophil apoptosis by down-regulation of Mcl-1.

Eosinophils are major players in inflammatory allergic diseases such as asthma, hay fever and eczema. Here we show that the cyclin-dependent kinase inhibitor (CDKi) R-roscovitine efficiently and rapidly induces human eosinophil apoptosis using flow cytometric analysis of annexin-V/propidium iodide staining, morphological analysis by light microscopy, transmission electron microscopy and Western immunoblotting for caspase-3 cleavage. We further dissect these observations by demonstrating that eosinophils treated with R-roscovitine lose mitochondrial membrane potential and the key survival protein Mcl-1 is down-regulated. This novel finding of efficacious induction of eosinophil apoptosis by CDKi drugs has potential as a strategy for driving resolution of eosinophilic inflammation.