In vitro activity: YM-90709 is a novel antagonist of interleukin-5 receptor which inhibits the binding of interleukin-5 to interleukin-5 receptor. YM-90709 inhibit the binding of IL-5 to its receptor on peripheral human eosinophils and butyric acid-treated eosinophilic HL-60 clone 15 cells, with IC50 values of 1.0 and 0.57 microM, respectively. Interleukin-5 (IL-5) plays an important role in the activation of eosinophils in allergic inflammation including asthma and atopic dermatitis. In contrast, YM-90709 did not affect the binding of granulocyte-macrophage colony-stimulating factor (GM-CSF) to its receptor on eosinophils and eosinophilic HL-60 clone 15 cells. In functional assays, YM-90709 inhibited IL-5-prolonged eosinophil survival with an IC50 value of 0.45 microM and did not affect the GM-CSF-prolonged eosinophil survival. Furthermore, YM-90709 inhibited the IL-5-induced but not GM-CSF-induced tyrosine phosphorylation of Janus kinase 2 (JAK2) in eosinophilic HL-60 clone 15 cells. These results indicate that YM-90709 is a novel IL-5 inhibitor which selectively blocks the binding of IL-5 to the IL-5 receptor (IL-5R).

Kinase Assay: YM-90709 is a novel antagonist of interleukin-5 receptor which inhibits the binding of interleukin-5 to interleukin-5 receptor. YM-90709 inhibit the binding of IL-5 to its receptor on peripheral human eosinophils and butyric acid-treated eosinophilic HL-60 clone 15 cells, with IC50 values of 1.0 and 0.57 microM, respectively.

Cell Assay: YM-90709 inhibited the IL-5-induced but not GM-CSF-induced tyrosine phosphorylation of Janus kinase 2 (JAK2) in eosinophilic HL-60 clone 15 cells. These results indicate that YM-90709 is a novel IL-5 inhibitor which selectively blocks the binding of IL-5 to the IL-5 receptor (IL-5R).