Purity ≥97% as determined by SDS-PAGE and HPLC. In response to the presence of allergens, this protein directly promotes the accumulation of eosinophils, a prominent feature of allergic inflammatory reactions. Binds to CCR3. Biological Activity: Fully biologically active when compared to standard. The biological activity determined by a chemotaxis bioassay using human peripheral blood eosinophils is in a concentration range of 0.1-10.0ng/ml.