Effect of a novel interleukin-5 receptor antagonist, YM-90709, on antigen-induced eosinophil infiltration into the airway of BDF1 mice.

A newly synthesized compound, YM-90709, 2,3-dimethoxy-6,6-dimethyl-5,6-dihydrobenzo[7,8]indolizino[2,3-b]quinoxaline, was previously reported to specifically inhibit the binding of interleukin-5 (IL-5) to its receptor (R) on human eosinophils. In this study, the intravenous injection of YM-90709 inhibited antigen-induced infiltration of eosinophils into the bronchoalveolar lavage fluid (BALF) of BDF1 mice, with an ED(50) value of 0.050mg/kg. Anti-murine IL-5 monoclonal antibody (mAb) also inhibited the infiltration of eosinophils with an ED(50) value of 0.035mg/kg. These results indicate that YM-90709, which is a novel IL-5R antagonist, inhibits antigen-induced eosinophil recruitment into the airway, the same as anti-IL-5 mAb does.